Arkaprabha Banerjee, Hyuntae Byun, Andrew J. Hrycko, Qinqin Pu, Mary R. Brockett, Nathaniel C. Esteves, Jennifer R. Miller, Qiushi Li, Amy T. Ma, Jun Zhu
Bacterial pathogens possess a remarkable capacity to sense and adapt to ever‐changing environments. For example, Vibrio cholerae, the causative agent of the severe diarrheal disease cholera, thrives in aquatic ecosystems and human hosts through dynamic survival strategies. In this study, we investigated the role of three photolyases, enzymes that repair DNA damage caused by exposure to UV radiation and blue light, in the environmental survival of V. cholerae. Among these, we identified cry1 as critical for resistance to blue light, as mutations in this gene, but not in the other photolyase genes, rendered V. cholerae susceptible to such stress. Expression of cry1 was induced by blue light and regulated by RpoE and the anti‐sigma factor ChrR. We further showed that nitric oxide (NO), a host‐derived stressor encountered during infection, also activated cry1 expression. We found that one of the two cysteine residues in ChrR was important for sensing reactive nitrogen species (RNS), thereby modulating cry1 expression. While Cry1 was not required for V. cholerae colonization in animal models, pre‐induction of Cry1 by RNS in vivo or in vitro enhanced V. cholerae resistance to blue light. These findings suggest that host‐derived NO encountered during infection primes V. cholerae for survival in blue‐light‐rich aquatic environments, supporting its transition between host and environmental niches.
{"title":"In Vivo Nitrosative Stress‐Induced Expression of a Photolyase Promotes Vibrio cholerae Environmental Blue Light Resistance","authors":"Arkaprabha Banerjee, Hyuntae Byun, Andrew J. Hrycko, Qinqin Pu, Mary R. Brockett, Nathaniel C. Esteves, Jennifer R. Miller, Qiushi Li, Amy T. Ma, Jun Zhu","doi":"10.1111/mmi.15340","DOIUrl":"https://doi.org/10.1111/mmi.15340","url":null,"abstract":"Bacterial pathogens possess a remarkable capacity to sense and adapt to ever‐changing environments. For example, <jats:styled-content style=\"fixed-case\"><jats:italic>Vibrio cholerae</jats:italic></jats:styled-content>, the causative agent of the severe diarrheal disease cholera, thrives in aquatic ecosystems and human hosts through dynamic survival strategies. In this study, we investigated the role of three photolyases, enzymes that repair DNA damage caused by exposure to UV radiation and blue light, in the environmental survival of <jats:styled-content style=\"fixed-case\"><jats:italic>V. cholerae</jats:italic></jats:styled-content>. Among these, we identified <jats:italic>cry1</jats:italic> as critical for resistance to blue light, as mutations in this gene, but not in the other photolyase genes, rendered <jats:styled-content style=\"fixed-case\"><jats:italic>V. cholerae</jats:italic></jats:styled-content> susceptible to such stress. Expression of <jats:italic>cry1</jats:italic> was induced by blue light and regulated by RpoE and the anti‐sigma factor ChrR. We further showed that nitric oxide (NO), a host‐derived stressor encountered during infection, also activated <jats:italic>cry1</jats:italic> expression. We found that one of the two cysteine residues in ChrR was important for sensing reactive nitrogen species (RNS), thereby modulating <jats:italic>cry1</jats:italic> expression. While Cry1 was not required for <jats:styled-content style=\"fixed-case\"><jats:italic>V. cholerae</jats:italic></jats:styled-content> colonization in animal models, pre‐induction of Cry1 by RNS in vivo or in vitro enhanced <jats:styled-content style=\"fixed-case\"><jats:italic>V. cholerae</jats:italic></jats:styled-content> resistance to blue light. These findings suggest that host‐derived NO encountered during infection primes <jats:styled-content style=\"fixed-case\"><jats:italic>V. cholerae</jats:italic></jats:styled-content> for survival in blue‐light‐rich aquatic environments, supporting its transition between host and environmental niches.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":"14 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142986273","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Spo0A in Bacillus subtilis is activated by phosphorylation (Spo0A~P) upon starvation and differentially controls a set of genes involved in biofilm formation and sporulation. The spo0A gene is transcribed by two distinct promoters, a σA-recognized upstream promoter Pv during growth, and a σH-recognized downstream promoter Ps during starvation, and appears to be autoregulated by four Spo0A~P binding sites (0A1-4 boxes) localized between two promoters. However, the autoregulatory mechanisms and their impact on differentiation remain elusive. Here, we determined the relative affinity of Spo0A~P for each 0A box and dissected each promoter in combination with the systematic 0A box mutations. The data revealed that (1) the Pv and Ps promoters are on and off, respectively, under nutrient-rich conditions without Spo0A~P, (2) the Ps promoter is activated by first 0A3 and then 0A1 during early starvation with low Spo0A~P, (3) during later starvation with high Spo0A~P, the Pv promoter is repressed by first 0A1 and then 0A2 and 0A4, and (4) during prolonged starvation, both promoters are silenced by all 0A boxes with very high Spo0A~P. Our results indicate that the autoregulation of spo0A is one of the key determinants to achieve a developmental increase in Spo0A~P, leading to a temporal window for entry into biofilm formation or sporulation.
{"title":"Autoregulation of the Master Regulator Spo0A Controls Cell-Fate Decisions in Bacillus subtilis","authors":"Brenda Zarazúa-Osorio, Priyanka Srivastava, Anuradha Marathe, Syeda Hira Zahid, Masaya Fujita","doi":"10.1111/mmi.15341","DOIUrl":"https://doi.org/10.1111/mmi.15341","url":null,"abstract":"Spo0A in <i>Bacillus subtilis</i> is activated by phosphorylation (Spo0A~P) upon starvation and differentially controls a set of genes involved in biofilm formation and sporulation. The <i>spo0A</i> gene is transcribed by two distinct promoters, a σ<sup>A</sup>-recognized upstream promoter Pv during growth, and a σ<sup>H</sup>-recognized downstream promoter Ps during starvation, and appears to be autoregulated by four Spo0A~P binding sites (0A1-4 boxes) localized between two promoters. However, the autoregulatory mechanisms and their impact on differentiation remain elusive. Here, we determined the relative affinity of Spo0A~P for each 0A box and dissected each promoter in combination with the systematic 0A box mutations. The data revealed that (1) the Pv and Ps promoters are on and off, respectively, under nutrient-rich conditions without Spo0A~P, (2) the Ps promoter is activated by first 0A3 and then 0A1 during early starvation with low Spo0A~P, (3) during later starvation with high Spo0A~P, the Pv promoter is repressed by first 0A1 and then 0A2 and 0A4, and (4) during prolonged starvation, both promoters are silenced by all 0A boxes with very high Spo0A~P. Our results indicate that the autoregulation of <i>spo0A</i> is one of the key determinants to achieve a developmental increase in Spo0A~P, leading to a temporal window for entry into biofilm formation or sporulation.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":"2 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2025-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142981669","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Monford Paul Abishek N, Xun Wang, Heung Jin Jeon, Heon M. Lim
The distance between the ribosome and the RNA polymerase active centers, known as the mRNA loop length, is crucial for transcription-translation coupling. Despite the existence of multiple expressomes with varying mRNA loop lengths, their in vivo roles remain largely unexplored. This study examines the mechanisms governing transcription termination in the Escherichia coli galactose operon, revealing a crucial role in the transcription and translation coupling state. The operon utilizes both Rho-independent and Rho-dependent terminators. Our findings demonstrate that long-loop coupled transcription-translation complexes preferentially terminate at the upstream Rho-independent terminator, while short-loop complexes bypass it, terminating at the downstream Rho-dependent terminator. The efficiency of the Rho-independent terminator is enhanced by an extended U-track, suggesting a novel mechanism to overcome ribosome inhibition. These results uncover a new regulatory layer in transcription termination, challenging the traditional view of this process as random and highlighting a predetermined mechanism based on the coupling state. We propose that tandem terminators may function as regulatory checkpoints under fluctuating ribosome-RNAP coupling conditions, which can occur due to specific cellular states or factors affecting ribosome or RNAP binding efficiency. This suggests a previously overlooked mechanism that could refine transcription termination choices and expand our understanding of transcription regulation.
{"title":"Deciphering the Coupling State-Dependent Transcription Termination in the Escherichia coli Galactose Operon","authors":"Monford Paul Abishek N, Xun Wang, Heung Jin Jeon, Heon M. Lim","doi":"10.1111/mmi.15339","DOIUrl":"https://doi.org/10.1111/mmi.15339","url":null,"abstract":"The distance between the ribosome and the RNA polymerase active centers, known as the mRNA loop length, is crucial for transcription-translation coupling. Despite the existence of multiple expressomes with varying mRNA loop lengths, their in vivo roles remain largely unexplored. This study examines the mechanisms governing transcription termination in the <i>Escherichia coli</i> galactose operon, revealing a crucial role in the transcription and translation coupling state. The operon utilizes both Rho-independent and Rho-dependent terminators. Our findings demonstrate that long-loop coupled transcription-translation complexes preferentially terminate at the upstream Rho-independent terminator, while short-loop complexes bypass it, terminating at the downstream Rho-dependent terminator. The efficiency of the Rho-independent terminator is enhanced by an extended U-track, suggesting a novel mechanism to overcome ribosome inhibition. These results uncover a new regulatory layer in transcription termination, challenging the traditional view of this process as random and highlighting a predetermined mechanism based on the coupling state. We propose that tandem terminators may function as regulatory checkpoints under fluctuating ribosome-RNAP coupling conditions, which can occur due to specific cellular states or factors affecting ribosome or RNAP binding efficiency. This suggests a previously overlooked mechanism that could refine transcription termination choices and expand our understanding of transcription regulation.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":"6 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2025-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142937692","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Suellen Rodrigues Maran, Ariely Barbosa Leite, Gabriela Gomes Alves, Bruno Souza Bonifácio, Carlos Eduardo Alves, Paulo Otávio Lourenço Moreira, Giovanna Marques Panessa, Heloísa Monteiro do Amaral Prado, Angélica Hollunder Klippel, José Renato Cussiol, Katlin Brauer Massirer, Tiago Rodrigues Ferreira, David Sacks, Clara Lúcia Barbiéri, Marcelo Santos da Silva, Rubens Lima do Monte‐Neto, Nilmar Silvio Moretti
Leishmania presents a complex life cycle that involves both invertebrate and vertebrate hosts. By regulating gene expression, protein synthesis, and metabolism, the parasite can adapt to various environmental conditions. This regulation occurs mainly at the post‐transcriptional level and may involve epitranscriptomic modifications of RNAs. Recent studies have shown that mRNAs in humans undergo a modification known as N4‐acetylcytidine (ac4C) catalyzed by the enzyme N‐acetyltransferase (NAT10), impacting mRNAs stability and translation. Here, we characterized the NAT10 homologue of L. mexicana, finding that the enzyme exhibits all the conserved acetyltransferase domains although failed to functionally complement the Kre33 mutant in Saccharomyces cerevisiae. We also discovered that LmexNAT10 is nuclear, and seems essential, as evidenced by unsuccessful attempts to obtain null mutant parasites. Phenotypic characterization of single‐knockout parasites revealed that LmexNAT10 affects the multiplication of procyclic forms and the promastigote‐amastigote differentiation. Additionally, in vivo infection studies using the invertebrate vector Lutzomyia longipalpis showed a delay in the parasite differentiation into metacyclics. Finally, we observed changes in the cell cycle progression and protein synthesis in the mutant parasites. Together, these results suggest that LmexNAT10 might be important for parasite differentiation, potentially by regulating ac4C levels.
{"title":"Leishmania mexicana N‐Acetyltransferease 10 Is Important for Polysome Formation and Cell Cycle Progression","authors":"Suellen Rodrigues Maran, Ariely Barbosa Leite, Gabriela Gomes Alves, Bruno Souza Bonifácio, Carlos Eduardo Alves, Paulo Otávio Lourenço Moreira, Giovanna Marques Panessa, Heloísa Monteiro do Amaral Prado, Angélica Hollunder Klippel, José Renato Cussiol, Katlin Brauer Massirer, Tiago Rodrigues Ferreira, David Sacks, Clara Lúcia Barbiéri, Marcelo Santos da Silva, Rubens Lima do Monte‐Neto, Nilmar Silvio Moretti","doi":"10.1111/mmi.15338","DOIUrl":"https://doi.org/10.1111/mmi.15338","url":null,"abstract":"<jats:italic>Leishmania</jats:italic> presents a complex life cycle that involves both invertebrate and vertebrate hosts. By regulating gene expression, protein synthesis, and metabolism, the parasite can adapt to various environmental conditions. This regulation occurs mainly at the post‐transcriptional level and may involve epitranscriptomic modifications of RNAs. Recent studies have shown that mRNAs in humans undergo a modification known as N4‐acetylcytidine (ac4C) catalyzed by the enzyme N‐acetyltransferase (NAT10), impacting mRNAs stability and translation. Here, we characterized the NAT10 homologue of <jats:styled-content style=\"fixed-case\"><jats:italic>L. mexicana</jats:italic></jats:styled-content>, finding that the enzyme exhibits all the conserved acetyltransferase domains although failed to functionally complement the Kre33 mutant in <jats:styled-content style=\"fixed-case\"><jats:italic>Saccharomyces cerevisiae</jats:italic></jats:styled-content>. We also discovered that LmexNAT10 is nuclear, and seems essential, as evidenced by unsuccessful attempts to obtain null mutant parasites. Phenotypic characterization of single‐knockout parasites revealed that LmexNAT10 affects the multiplication of procyclic forms and the promastigote‐amastigote differentiation. Additionally, in vivo infection studies using the invertebrate vector <jats:italic>Lutzomyia longipalpis</jats:italic> showed a delay in the parasite differentiation into metacyclics. Finally, we observed changes in the cell cycle progression and protein synthesis in the mutant parasites. Together, these results suggest that LmexNAT10 might be important for parasite differentiation, potentially by regulating ac4C levels.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":"34 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2025-01-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142925086","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Marshall Jaroch, Kathryn Savage, Paul Kuipers, Jo Marie Bacusmo, Jennifer Hu, Jingjing Sun, Peter C. Dedon, Kelly C. Rice, Valérie de Crécy‐Lagard
Queuosine (Q) is a modification of the wobble base in tRNAs that decode NA(C/U) codons. It is ubiquitous in bacteria, including many pathogens. Streptococcus mutans is an early colonizer of dental plaque biofilm and a key player in dental caries. Using a combination of genetic and physiological approaches, the predicted Q synthesis and salvage pathways were validated in this organism. These experiments confirmed that S. mutans can synthesize Q de novo through similar pathways found in Bacillus subtilis and Escherichia coli. However, S. mutans has a distinct salvage pathway compared to these model organisms, as it uses a transporter belonging to the energy coupling factor (ECF) family controlled by a preQ1‐dependent riboswitch. Furthermore, Q levels in this oral pathogen depended heavily on the media composition, suggesting that micronutrients can affect Q‐mediated translation efficiency.
Queuosine (Q)是trna中对NA（C/U）密码子进行解码的摆动碱基的修饰。它在细菌中无处不在，包括许多病原体。变形链球菌是牙菌斑生物膜的早期定植者，是龋病的重要参与者。利用遗传和生理方法的结合，预测的Q合成和回收途径在该生物体中得到验证。这些实验证实，变形链球菌可以通过与枯草芽孢杆菌和大肠杆菌相似的途径合成Q de novo。然而，与这些模式生物相比，变形链球菌具有独特的挽救途径，因为它使用属于能量偶联因子（ECF）家族的转运体，该转运体由preQ1依赖的核糖开关控制。此外，这种口腔病原体的Q水平很大程度上取决于培养基的组成，这表明微量营养素可以影响Q介导的翻译效率。
{"title":"Environmental Control of Queuosine Levels in Streptococcus mutanstRNAs","authors":"Marshall Jaroch, Kathryn Savage, Paul Kuipers, Jo Marie Bacusmo, Jennifer Hu, Jingjing Sun, Peter C. Dedon, Kelly C. Rice, Valérie de Crécy‐Lagard","doi":"10.1111/mmi.15336","DOIUrl":"https://doi.org/10.1111/mmi.15336","url":null,"abstract":"Queuosine (Q) is a modification of the wobble base in tRNAs that decode NA(C/U) codons. It is ubiquitous in bacteria, including many pathogens. <jats:styled-content style=\"fixed-case\"><jats:italic>Streptococcus mutans</jats:italic></jats:styled-content> is an early colonizer of dental plaque biofilm and a key player in dental caries. Using a combination of genetic and physiological approaches, the predicted <jats:italic>Q</jats:italic> synthesis and salvage pathways were validated in this organism. These experiments confirmed that <jats:styled-content style=\"fixed-case\"><jats:italic>S. mutans</jats:italic></jats:styled-content> can synthesize <jats:italic>Q de novo</jats:italic> through similar pathways found in <jats:styled-content style=\"fixed-case\"><jats:italic>Bacillus subtilis</jats:italic></jats:styled-content> and <jats:styled-content style=\"fixed-case\"><jats:italic>Escherichia coli</jats:italic></jats:styled-content>. However, <jats:styled-content style=\"fixed-case\"><jats:italic>S. mutans</jats:italic></jats:styled-content> has a distinct salvage pathway compared to these model organisms, as it uses a transporter belonging to the energy coupling factor (ECF) family controlled by a preQ<jats:sub>1</jats:sub>‐dependent riboswitch. Furthermore, Q levels in this oral pathogen depended heavily on the media composition, suggesting that micronutrients can affect Q‐mediated translation efficiency.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":"8 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2024-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142884189","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
DNA topology is a direct consequence of the double helical nature of DNA and is defined by how the two complementary DNA strands are intertwined. Virtually every reaction involving DNA is influenced by DNA topology or has topological effects. It is therefore of fundamental importance to understand how this phenomenon is controlled in living cells. DNA topoisomerases are the key actors dedicated to the regulation of DNA topology in cells from all domains of life. While significant progress has been made in the last two decades in understanding how these enzymes operate in vivo in Bacteria and Eukaryotes, studies in Archaea have been lagging behind. This review article aims to summarize what is currently known about DNA topology regulation by DNA topoisomerases in main archaeal model organisms. These model archaea exhibit markedly different lifestyles, genome organization and topoisomerase content, thus highlighting the diversity and the complexity of DNA topology regulation mechanisms and their evolution in this domain of life. The recent development of functional genomic assays supported by next-generation sequencing now allows to delve deeper into this timely and exciting, yet still understudied topic.
{"title":"Regulation of DNA Topology in Archaea: State of the Art and Perspectives","authors":"Paul Villain, Tamara Basta","doi":"10.1111/mmi.15328","DOIUrl":"https://doi.org/10.1111/mmi.15328","url":null,"abstract":"DNA topology is a direct consequence of the double helical nature of DNA and is defined by how the two complementary DNA strands are intertwined. Virtually every reaction involving DNA is influenced by DNA topology or has topological effects. It is therefore of fundamental importance to understand how this phenomenon is controlled in living cells. DNA topoisomerases are the key actors dedicated to the regulation of DNA topology in cells from all domains of life. While significant progress has been made in the last two decades in understanding how these enzymes operate in vivo in Bacteria and Eukaryotes, studies in Archaea have been lagging behind. This review article aims to summarize what is currently known about DNA topology regulation by DNA topoisomerases in main archaeal model organisms. These model archaea exhibit markedly different lifestyles, genome organization and topoisomerase content, thus highlighting the diversity and the complexity of DNA topology regulation mechanisms and their evolution in this domain of life. The recent development of functional genomic assays supported by next-generation sequencing now allows to delve deeper into this timely and exciting, yet still understudied topic.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":"112 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2024-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142870016","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Cyanobacteria developed oxygenic photosynthesis and represent the phylogenetic ancestors of chloroplasts. The model strain Anabaena sp. strain PCC 7120 grows as filaments of communicating cells and can form heterocysts, cells specialized for N2 fixation. In the Anabaena genome, ORF all2390 is annotated as encoding a SulA homolog, but sequence similarity to SulA of model bacteria is insignificant. We generated strains that lacked or overexpressed all2390, both of which showed instances of increased cell size, and observed that purified All2390 protein interfered with the in vitro polymerization of FtsZ. Heterocyst frequency diminished by all2390 inactivation and increased by all2390 overexpression. Overexpression retarded the dismantlement of Z-ring structures that determines commitment in the differentiating cells. Thus, All2390 can influence cell division affecting heterocyst differentiation. An All2390-GFP fusion protein localized to the thylakoid membranes including the honeycomb membranes, which harbor photosynthetic complexes, in the heterocyst polar regions. Notably, all2390 expression strongly increased under high light, conditions under which growth of the null mutant is compromised. Thus, All2390 appears essential for adaptation to high light conditions. We named All2390 ThyD to reflect its thylakoidal localization and its dual role in cell division dynamics and acclimation of thylakoid membranes to increased light intensity.
{"title":"ThyD Is a Thylakoid Membrane Protein Influencing Cell Division and Acclimation to High Light in the Multicellular Cyanobacterium Anabaena sp. Strain PCC 7120","authors":"Ana Valladares, Antonia Herrero","doi":"10.1111/mmi.15335","DOIUrl":"https://doi.org/10.1111/mmi.15335","url":null,"abstract":"Cyanobacteria developed oxygenic photosynthesis and represent the phylogenetic ancestors of chloroplasts. The model strain <i>Anabaena</i> sp. strain PCC 7120 grows as filaments of communicating cells and can form heterocysts, cells specialized for N<sub>2</sub> fixation. In the <i>Anabaena</i> genome, ORF all2390 is annotated as encoding a SulA homolog, but sequence similarity to SulA of model bacteria is insignificant. We generated strains that lacked or overexpressed all2390, both of which showed instances of increased cell size, and observed that purified All2390 protein interfered with the in vitro polymerization of FtsZ. Heterocyst frequency diminished by all2390 inactivation and increased by all2390 overexpression. Overexpression retarded the dismantlement of Z-ring structures that determines commitment in the differentiating cells. Thus, All2390 can influence cell division affecting heterocyst differentiation. An All2390-GFP fusion protein localized to the thylakoid membranes including the <i>honeycomb</i> membranes, which harbor photosynthetic complexes, in the heterocyst polar regions. Notably, all2390 expression strongly increased under high light, conditions under which growth of the null mutant is compromised. Thus, All2390 appears essential for adaptation to high light conditions. We named All2390 ThyD to reflect its thylakoidal localization and its dual role in cell division dynamics and acclimation of thylakoid membranes to increased light intensity.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":"12 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2024-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142763483","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Johannes Allweier, Michael Bartels, Hanifeh Torabi, Maria del Pilar Martinez Tauler, Nahla Galal Metwally, Thomas Roeder, Thomas Gutsmann, Iris Bruchhaus
Malaria remains a significant global health problem, mainly due to Plasmodium falciparum, which is responsible for most fatal infections. Infected red blood cells (iRBCs) evade spleen clearance by adhering to endothelial cells (ECs), triggering capillary blockage, inflammation, endothelial dysfunction and altered vascular permeability, prompting an endothelial transcriptional response. The iRBCIT4var04/HBEC-5i model, where iRBCs present IT4var04 (VAR2CSA) on their surface, was used to analyze the effects of iRBC binding on ECs at different temperature (37°C vs. 40°C). Binding of non-infected RBCs (niRBCs) and fever alone altered the expression of hundreds of genes in ECs. Comparing the expression profile of HBEC-5i cells cultured either in the presence of iRBCs or in the presence of niRBCs revealed significant upregulation of genes linked to immune response, nucleosome assembly, NF-kappa B signaling, angiogenesis, and antiviral immune response/interferon-alpha/beta signaling. Raising the temperature to 40°C, simulating fever, led to further upregulation of many genes, particularly those involved in cytokine production and angiogenesis. In summary, the presence of iRBCs stimulates ECs, activating several immunological pathways and affecting antiviral (−parasitic) mechanisms and angiogenesis. Our data uncovered the induction of the interferon-alpha/beta signaling pathway in ECs in response to iRBCs.
{"title":"Cytoadhesion of Plasmodium falciparum-Infected Red Blood Cells Changes the Expression of Cytokine-, Histone- and Antiviral Protein-Encoding Genes in Brain Endothelial Cells","authors":"Johannes Allweier, Michael Bartels, Hanifeh Torabi, Maria del Pilar Martinez Tauler, Nahla Galal Metwally, Thomas Roeder, Thomas Gutsmann, Iris Bruchhaus","doi":"10.1111/mmi.15331","DOIUrl":"https://doi.org/10.1111/mmi.15331","url":null,"abstract":"Malaria remains a significant global health problem, mainly due to <i>Plasmodium falciparum</i>, which is responsible for most fatal infections. Infected red blood cells (iRBCs) evade spleen clearance by adhering to endothelial cells (ECs), triggering capillary blockage, inflammation, endothelial dysfunction and altered vascular permeability, prompting an endothelial transcriptional response. The iRBC<sup>IT4var04</sup>/HBEC-5i model, where iRBCs present IT4var04 (VAR2CSA) on their surface, was used to analyze the effects of iRBC binding on ECs at different temperature (37°C vs. 40°C). Binding of non-infected RBCs (niRBCs) and fever alone altered the expression of hundreds of genes in ECs. Comparing the expression profile of HBEC-5i cells cultured either in the presence of iRBCs or in the presence of niRBCs revealed significant upregulation of genes linked to immune response, nucleosome assembly, NF-kappa B signaling, angiogenesis, and antiviral immune response/interferon-alpha/beta signaling. Raising the temperature to 40°C, simulating fever, led to further upregulation of many genes, particularly those involved in cytokine production and angiogenesis. In summary, the presence of iRBCs stimulates ECs, activating several immunological pathways and affecting antiviral (−parasitic) mechanisms and angiogenesis. Our data uncovered the induction of the interferon-alpha/beta signaling pathway in ECs in response to iRBCs.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":"262 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2024-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142763484","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Christopher J. Presloid, Jialiu Jiang, Pratistha Kandel, Henry R. Anderson, Patrick C. Beardslee, Thomas M. Swayne, Karl R. Schmitz
Drug-resistant tuberculosis infections are a major threat to global public health. The essential mycobacterial ClpC1P1P2 protease has received attention as a prospective target for novel antibacterial therapeutics. However, efforts to probe its function in cells are constrained by our limited knowledge of its physiological proteolytic repertoire. Here, we interrogate the role of mycobacterial ClpS in directing N-degron pathway proteolysis by ClpC1P1P2 in Mycolicibacterium smegmatis. Binding assays demonstrate that mycobacterial ClpS binds canonical primary destabilizing residues (Leu, Phe, Tyr, Trp) with moderate affinity. N-degron binding restricts the conformational flexibility of a loop adjacent to the ClpS N-degron binding pocket and strengthens ClpS•ClpC1 binding affinity ~30-fold, providing a mechanism for cells to prioritize N-degron proteolysis when substrates are abundant. Proteolytic reporter assays in M. smegmatis confirm degradation of substrates bearing primary N-degrons, but suggest that secondary N-degrons are absent in mycobacteria. This work expands our understanding of the mycobacterial N-degron pathway and identifies ClpS as a critical component for substrate specificity, providing insights that may support the development of improved Clp protease inhibitors.
{"title":"ClpS Directs Degradation of N-Degron Substrates With Primary Destabilizing Residues in Mycolicibacterium smegmatis","authors":"Christopher J. Presloid, Jialiu Jiang, Pratistha Kandel, Henry R. Anderson, Patrick C. Beardslee, Thomas M. Swayne, Karl R. Schmitz","doi":"10.1111/mmi.15334","DOIUrl":"https://doi.org/10.1111/mmi.15334","url":null,"abstract":"Drug-resistant tuberculosis infections are a major threat to global public health. The essential mycobacterial ClpC1P1P2 protease has received attention as a prospective target for novel antibacterial therapeutics. However, efforts to probe its function in cells are constrained by our limited knowledge of its physiological proteolytic repertoire. Here, we interrogate the role of mycobacterial ClpS in directing N-degron pathway proteolysis by ClpC1P1P2 in <i>Mycolicibacterium smegmatis</i>. Binding assays demonstrate that mycobacterial ClpS binds canonical primary destabilizing residues (Leu, Phe, Tyr, Trp) with moderate affinity. N-degron binding restricts the conformational flexibility of a loop adjacent to the ClpS N-degron binding pocket and strengthens ClpS•ClpC1 binding affinity ~30-fold, providing a mechanism for cells to prioritize N-degron proteolysis when substrates are abundant. Proteolytic reporter assays in <i>M. smegmatis</i> confirm degradation of substrates bearing primary N-degrons, but suggest that secondary N-degrons are absent in mycobacteria. This work expands our understanding of the mycobacterial N-degron pathway and identifies ClpS as a critical component for substrate specificity, providing insights that may support the development of improved Clp protease inhibitors.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":"116 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2024-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142763487","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
TonB is an essential component of an energy-generating system that powers active transport across the outer membrane (OM) of compounds that are too large or too scarce to diffuse through porins. The TonB-dependent OM transport proteins (TBDTs) consist of β barrels forming pores that are closed by plugs. The binding of TonB to TBDTs elicits plug movement, which opens the pores and enables nutrient translocation from the cell surface into the periplasm. TonB is also involved in the uptake of certain proteins, particularly toxins, through OM proteins that differ structurally from TBDTs. TonB binds to a sequence of five residues, designated as the TonB box, which is conserved in all TBDTs. Energy from the proton motive force (pmf) of the cytoplasmic membrane is transmitted to TonB by two proteins, ExbB and ExbD. These proteins form an energy-transmitting protein complex consisting of five ExbB proteins, forming a pore that encloses the ExbD dimer. This review discusses the structural changes that occur in TBDTs upon interaction with TonB, as well as the interaction of ExbB-ExbD with TonB, which is required to transmit the energy of the pmf and thereby open TBDT pores. TonB facilitates import of a wide range of substrates.
{"title":"Substrate Uptake by TonB-Dependent Outer Membrane Transporters","authors":"Volkmar Braun","doi":"10.1111/mmi.15332","DOIUrl":"https://doi.org/10.1111/mmi.15332","url":null,"abstract":"TonB is an essential component of an energy-generating system that powers active transport across the outer membrane (OM) of compounds that are too large or too scarce to diffuse through porins. The TonB-dependent OM transport proteins (TBDTs) consist of β barrels forming pores that are closed by plugs. The binding of TonB to TBDTs elicits plug movement, which opens the pores and enables nutrient translocation from the cell surface into the periplasm. TonB is also involved in the uptake of certain proteins, particularly toxins, through OM proteins that differ structurally from TBDTs. TonB binds to a sequence of five residues, designated as the TonB box, which is conserved in all TBDTs. Energy from the proton motive force (pmf) of the cytoplasmic membrane is transmitted to TonB by two proteins, ExbB and ExbD. These proteins form an energy-transmitting protein complex consisting of five ExbB proteins, forming a pore that encloses the ExbD dimer. This review discusses the structural changes that occur in TBDTs upon interaction with TonB, as well as the interaction of ExbB-ExbD with TonB, which is required to transmit the energy of the pmf and thereby open TBDT pores. TonB facilitates import of a wide range of substrates.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":"13 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2024-12-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142763486","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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