Pub Date : 2024-05-01Epub Date: 2024-03-25DOI: 10.1111/mmi.15254
Nerina Jusufovic, Andrew C Krusenstjerna, Christina R Savage, Timothy C Saylor, Catherine A Brissette, Wolfram R Zückert, Paula J Schlax, Md A Motaleb, Brian Stevenson
The PilZ domain-containing protein, PlzA, is the only known cyclic di-GMP binding protein encoded by all Lyme disease spirochetes. PlzA has been implicated in the regulation of many borrelial processes, but the effector mechanism of PlzA was not previously known. Here, we report that PlzA can bind DNA and RNA and that nucleic acid binding requires c-di-GMP, with the affinity of PlzA for nucleic acids increasing as concentrations of c-di-GMP were increased. A mutant PlzA that is incapable of binding c-di-GMP did not bind to any tested nucleic acids. We also determined that PlzA interacts predominantly with the major groove of DNA and that sequence length and G-C content play a role in DNA binding affinity. PlzA is a dual-domain protein with a PilZ-like N-terminal domain linked to a canonical C-terminal PilZ domain. Dissection of the domains demonstrated that the separated N-terminal domain bound nucleic acids independently of c-di-GMP. The C-terminal domain, which includes the c-di-GMP binding motifs, did not bind nucleic acids under any tested conditions. Our data are supported by computational docking, which predicts that c-di-GMP binding at the C-terminal domain stabilizes the overall protein structure and facilitates PlzA-DNA interactions via residues in the N-terminal domain. Based on our data, we propose that levels of c-di-GMP during the various stages of the enzootic life cycle direct PlzA binding to regulatory targets.
含 PilZ 结构域的蛋白 PlzA 是所有莱姆病螺旋体编码的唯一已知环状二-GMP 结合蛋白。PlzA 与许多包虫过程的调控有关，但其作用机制以前并不清楚。在这里，我们报告了 PlzA 能与 DNA 和 RNA 结合，并且核酸结合需要 c-di-GMP 的支持，随着 c-di-GMP 浓度的增加，PlzA 对核酸的亲和力也会增加。不能与 c-di-GMP 结合的突变体 PlzA 不与任何测试的核酸结合。我们还确定 PlzA 主要与 DNA 的主沟相互作用，序列长度和 G-C 含量在 DNA 结合亲和力中起作用。PlzA 是一种双结构域蛋白，其 N 端 PilZ 样结构域与 C 端 PilZ 结构域相连。对这两个结构域的剖析表明，分离的 N 端结构域与核酸的结合与 c-di-GMP 无关。包括 c-di-GMP 结合基团的 C 端结构域在任何测试条件下都不与核酸结合。我们的数据得到了计算对接的支持，计算对接预测 C 端结构域的 c-di-GMP 结合能稳定蛋白质的整体结构，并通过 N 端结构域的残基促进 PlzA-DNA 的相互作用。根据我们的数据，我们认为在enzootic生命周期的不同阶段，c-di-GMP的水平会引导PlzA与调控靶标结合。
{"title":"Borrelia burgdorferi PlzA is a cyclic-di-GMP dependent DNA and RNA binding protein.","authors":"Nerina Jusufovic, Andrew C Krusenstjerna, Christina R Savage, Timothy C Saylor, Catherine A Brissette, Wolfram R Zückert, Paula J Schlax, Md A Motaleb, Brian Stevenson","doi":"10.1111/mmi.15254","DOIUrl":"10.1111/mmi.15254","url":null,"abstract":"<p><p>The PilZ domain-containing protein, PlzA, is the only known cyclic di-GMP binding protein encoded by all Lyme disease spirochetes. PlzA has been implicated in the regulation of many borrelial processes, but the effector mechanism of PlzA was not previously known. Here, we report that PlzA can bind DNA and RNA and that nucleic acid binding requires c-di-GMP, with the affinity of PlzA for nucleic acids increasing as concentrations of c-di-GMP were increased. A mutant PlzA that is incapable of binding c-di-GMP did not bind to any tested nucleic acids. We also determined that PlzA interacts predominantly with the major groove of DNA and that sequence length and G-C content play a role in DNA binding affinity. PlzA is a dual-domain protein with a PilZ-like N-terminal domain linked to a canonical C-terminal PilZ domain. Dissection of the domains demonstrated that the separated N-terminal domain bound nucleic acids independently of c-di-GMP. The C-terminal domain, which includes the c-di-GMP binding motifs, did not bind nucleic acids under any tested conditions. Our data are supported by computational docking, which predicts that c-di-GMP binding at the C-terminal domain stabilizes the overall protein structure and facilitates PlzA-DNA interactions via residues in the N-terminal domain. Based on our data, we propose that levels of c-di-GMP during the various stages of the enzootic life cycle direct PlzA binding to regulatory targets.</p>","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":null,"pages":null},"PeriodicalIF":2.6,"publicationDate":"2024-05-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140288522","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}
Latent tuberculosis, caused by dormant Mycobacterium tuberculosis (Mtb), poses a threat to global health through the incubation of undiagnosed infections within the community. Dormant Mtb, which is phenotypically tolerant to antibiotics, accumulates triacylglycerol (TAG) utilizing fatty acids obtained from macrophage lipid droplets. TAG is vital to mycobacteria, serving as a cell envelope component and energy reservoir during latency. TAG synthesis occurs by sequential acylation of glycerol-3-phosphate, wherein the second acylation step is catalyzed by acylglycerol-3-phosphate acyltransferase (AGPAT), resulting in the production of phosphatidic acid (PA), a precursor for the synthesis of TAG and various phospholipids. Here, we have characterized a putative acyltransferase of Mtb encoded by Rv3816c. We found that Rv3816c has all four characteristic motifs of AGPAT, exists as a membrane-bound enzyme, and functions as 1-acylglycerol-3-phosphate acyltransferase. The enzyme could transfer the acyl group to acylglycerol-3-phosphate (LPA) from monounsaturated fatty acyl-coenzyme A of chain length 16 or 18 to produce PA. Complementation of Escherichia coli PlsC mutant in vivo by Rv3816c confirmed that it functions as AGPAT. Its active site mutants, H43A and D48A, were incapable of transferring the acyl group to LPA in vitro and were not able to rescue the growth defect of E. coli PlsC mutant in vivo. Identifying Rv3816c as AGPAT and comparing its properties with other AGPAT homologs is not only a step toward understanding the TAG biosynthesis in mycobacteria but has the potential to explore it as a drug target.
{"title":"Identification of a 1-acyl-glycerol-3-phosphate acyltransferase from Mycobacterium tuberculosis, a key enzyme involved in triacylglycerol biosynthesis","authors":"Meghna Santoshi, Harsh Bansia, Muzammil Hussain, Abodh Kumar Jha, Valakunja Nagaraja","doi":"10.1111/mmi.15265","DOIUrl":"https://doi.org/10.1111/mmi.15265","url":null,"abstract":"Latent tuberculosis, caused by dormant <i>Mycobacterium tuberculosis</i> (<i>Mtb</i>), poses a threat to global health through the incubation of undiagnosed infections within the community. Dormant <i>Mtb</i>, which is phenotypically tolerant to antibiotics, accumulates triacylglycerol (TAG) utilizing fatty acids obtained from macrophage lipid droplets. TAG is vital to mycobacteria, serving as a cell envelope component and energy reservoir during latency. TAG synthesis occurs by sequential acylation of glycerol-3-phosphate, wherein the second acylation step is catalyzed by acylglycerol-3-phosphate acyltransferase (AGPAT), resulting in the production of phosphatidic acid (PA), a precursor for the synthesis of TAG and various phospholipids. Here, we have characterized a putative acyltransferase of <i>Mtb</i> encoded by Rv3816c. We found that Rv3816c has all four characteristic motifs of AGPAT, exists as a membrane-bound enzyme, and functions as 1-acylglycerol-3-phosphate acyltransferase. The enzyme could transfer the acyl group to acylglycerol-3-phosphate (LPA) from monounsaturated fatty acyl-coenzyme A of chain length 16 or 18 to produce PA. Complementation of <i>Escherichia coli</i> PlsC mutant in vivo by Rv3816c confirmed that it functions as AGPAT. Its active site mutants, H43A and D48A, were incapable of transferring the acyl group to LPA in vitro and were not able to rescue the growth defect of <i>E. coli</i> PlsC mutant in vivo. Identifying Rv3816c as AGPAT and comparing its properties with other AGPAT homologs is not only a step toward understanding the TAG biosynthesis in mycobacteria but has the potential to explore it as a drug target.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":null,"pages":null},"PeriodicalIF":3.6,"publicationDate":"2024-04-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140651800","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}
Regulation of bacterial transcription is a complex and multi-faceted phenomenon that is critical for growth and adaptation. Proteins in the CarD_CdnL_TRCF family are widespread, often essential, regulators of transcription of genes required for growth and metabolic homeostasis. Research in the last decade has described the mechanistic and structural bases of CarD-CdnL-mediated regulation of transcription initiation. More recently, studies in a range of bacteria have begun to elucidate the physiological roles of CarD-CdnL proteins as well as mechanisms by which these proteins, themselves, are regulated. A theme has emerged wherein regulation of CarD-CdnL proteins is central to bacterial adaptation to stress and/or changing environmental conditions.
{"title":"House of CarDs: Functional insights into the transcriptional regulator CdnL","authors":"Erika L. Smith, Erin D. Goley","doi":"10.1111/mmi.15268","DOIUrl":"https://doi.org/10.1111/mmi.15268","url":null,"abstract":"Regulation of bacterial transcription is a complex and multi-faceted phenomenon that is critical for growth and adaptation. Proteins in the CarD_CdnL_TRCF family are widespread, often essential, regulators of transcription of genes required for growth and metabolic homeostasis. Research in the last decade has described the mechanistic and structural bases of CarD-CdnL-mediated regulation of transcription initiation. More recently, studies in a range of bacteria have begun to elucidate the physiological roles of CarD-CdnL proteins as well as mechanisms by which these proteins, themselves, are regulated. A theme has emerged wherein regulation of CarD-CdnL proteins is central to bacterial adaptation to stress and/or changing environmental conditions.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":null,"pages":null},"PeriodicalIF":3.6,"publicationDate":"2024-04-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140651406","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}
Entamoeba histolytica causes invasive amoebiasis, an important neglected tropical disease with a significant global health impact. The pathogenicity and survival of E. histolytica and its reptilian equivalent, Entamoeba invadens, relies on its ability to exhibit efficient motility, evade host immune responses, and exploit host resources, all of which are governed by the actin cytoskeleton remodeling. Our study demonstrates the early origin and the regulatory role of TALE homeobox protein EiHbox1 in actin‐related cellular processes. Several genes involved in different biological pathways, including actin dynamics are differentially expressed in EiHbox1 silenced cells. EiHbox1 silenced parasites showed disrupted F‐actin organization and loss of cellular polarity. EiHbox1's presence in the anterior region of migrating cells further suggests its involvement in maintaining cellular polarity. Loss of polarized morphology of EiHbox1 silenced parasites leads to altered motility from fast, directionally persistent, and highly chemotactic to slow, random, and less chemotactic, which subsequently leads to defective aggregation during encystation. EiHbox1 knockdown also resulted in a significant reduction in phagocytic capacity and poor capping response. These findings highlight the importance of EiHbox1 of E. invadens in governing cellular processes crucial for their survival, pathogenicity, and evasion of the host immune system.
{"title":"Ancestral TALE homeobox protein transcription factor regulates actin dynamics and cellular activities of protozoan parasite Entamoeba invadens","authors":"Meenakshi Pandey, Shilpa Sarkar, Sudip K. Ghosh","doi":"10.1111/mmi.15266","DOIUrl":"https://doi.org/10.1111/mmi.15266","url":null,"abstract":"<jats:italic>Entamoeba histolytica</jats:italic> causes invasive amoebiasis, an important neglected tropical disease with a significant global health impact. The pathogenicity and survival of <jats:italic>E. histolytica</jats:italic> and its reptilian equivalent, <jats:italic>Entamoeba invadens</jats:italic>, relies on its ability to exhibit efficient motility, evade host immune responses, and exploit host resources, all of which are governed by the actin cytoskeleton remodeling. Our study demonstrates the early origin and the regulatory role of TALE homeobox protein EiHbox1 in actin‐related cellular processes. Several genes involved in different biological pathways, including actin dynamics are differentially expressed in EiHbox1 silenced cells. EiHbox1 silenced parasites showed disrupted F‐actin organization and loss of cellular polarity. EiHbox1's presence in the anterior region of migrating cells further suggests its involvement in maintaining cellular polarity. Loss of polarized morphology of EiHbox1 silenced parasites leads to altered motility from fast, directionally persistent, and highly chemotactic to slow, random, and less chemotactic, which subsequently leads to defective aggregation during encystation. EiHbox1 knockdown also resulted in a significant reduction in phagocytic capacity and poor capping response. These findings highlight the importance of EiHbox1 of <jats:italic>E. invadens</jats:italic> in governing cellular processes crucial for their survival, pathogenicity, and evasion of the host immune system.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":null,"pages":null},"PeriodicalIF":3.6,"publicationDate":"2024-04-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140642513","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}
Sali M. Morris, Laura Wiens, Olivia Rose, Georg Fritz, Tim Rogers, Susanne Gebhard
Enterococcal infections frequently show high levels of antibiotic resistance, including to cell envelope‐acting antibiotics like daptomycin (DAP). While we have a good understanding of the resistance mechanisms, less is known about the control of such resistance genes in enterococci. Previous work unveiled a bacitracin resistance network, comprised of the sensory ABC transporter SapAB, the two‐component system (TCS) SapRS and the resistance ABC transporter RapAB. Interestingly, components of this system have recently been implicated in DAP resistance, a role usually regulated by the TCS LiaFSR. To better understand the regulation of DAP resistance and how this relates to mutations observed in DAP‐resistant clinical isolates of enterococci, we here explored the interplay between these two regulatory pathways. Our results show that SapR regulates an additional resistance operon, dltXABCD, a known DAP resistance determinant, and show that LiaFSR regulates the expression of sapRS. This regulatory structure places SapRS‐target genes under dual control, where expression is directly controlled by SapRS, which itself is up‐regulated through LiaFSR. The network structure described here shows how Enterococcus faecalis coordinates its response to cell envelope attack and can explain why clinical DAP resistance often emerges via mutations in regulatory components.
{"title":"Regulatory interactions between daptomycin‐ and bacitracin‐responsive pathways coordinate the cell envelope antibiotic resistance response of Enterococcus faecalis","authors":"Sali M. Morris, Laura Wiens, Olivia Rose, Georg Fritz, Tim Rogers, Susanne Gebhard","doi":"10.1111/mmi.15264","DOIUrl":"https://doi.org/10.1111/mmi.15264","url":null,"abstract":"Enterococcal infections frequently show high levels of antibiotic resistance, including to cell envelope‐acting antibiotics like daptomycin (DAP). While we have a good understanding of the resistance mechanisms, less is known about the control of such resistance genes in enterococci. Previous work unveiled a bacitracin resistance network, comprised of the sensory ABC transporter SapAB, the two‐component system (TCS) SapRS and the resistance ABC transporter RapAB. Interestingly, components of this system have recently been implicated in DAP resistance, a role usually regulated by the TCS LiaFSR. To better understand the regulation of DAP resistance and how this relates to mutations observed in DAP‐resistant clinical isolates of enterococci, we here explored the interplay between these two regulatory pathways. Our results show that SapR regulates an additional resistance operon, <jats:italic>dltXABCD</jats:italic>, a known DAP resistance determinant, and show that LiaFSR regulates the expression of <jats:italic>sapRS</jats:italic>. This regulatory structure places SapRS‐target genes under dual control, where expression is directly controlled by SapRS, which itself is up‐regulated through LiaFSR. The network structure described here shows how <jats:italic>Enterococcus faecalis</jats:italic> coordinates its response to cell envelope attack and can explain why clinical DAP resistance often emerges via mutations in regulatory components.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":null,"pages":null},"PeriodicalIF":3.6,"publicationDate":"2024-04-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140636451","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}
Jianhui Guo, Yan Yan, Jinhan Sun, Kai Ji, Zhiping Hei, Liang Zeng, Huanzhou Xu, Xiang Ren, Yuning Sun
Minute virus of canines (MVC) belongs to the genus Bocaparvovirus (formerly Bocavirus) within the Parvoviridae family and causes serious respiratory and gastrointestinal symptoms in neonatal canines worldwide. A productive viral infection relies on the successful recruitment of host factors for various stages of the viral life cycle. However, little is known about the MVC‐host cell interactions. In this study, we identified that two cellular proteins (Hsc70 and Hsp70) interacted with NS1 and VP2 proteins of MVC, and both two domains of Hsc70/Hsp70 were mediated for their interactions. Functional studies revealed that Hsp70 was induced by MVC infection, knockdown of Hsc70 considerably suppressed MVC replication, whereas the replication was dramatically promoted by Hsp70 knockdown. It is interesting that low amounts of overexpressed Hsp70 enhanced viral protein expression and virus production, but high amounts of Hsp70 overexpression weakened them. Upon Hsp70 overexpressing, we observed that the ubiquitination of viral proteins changed with Hsp70 overexpression, and proteasome inhibitor (MG132) restored an accumulation of viral proteins. In addition, we verified that Hsp70 family inhibitors remarkably decreased MVC replication. Overall, we identified Hsc70 and Hsp70 as interactors of MVC NS1 and VP2 proteins and were involved in MVC replication, which may provide novel targets for anti‐MVC approach.
{"title":"Chaperones Hsc70 and Hsp70 play distinct roles in the replication of bocaparvovirus minute virus of canines","authors":"Jianhui Guo, Yan Yan, Jinhan Sun, Kai Ji, Zhiping Hei, Liang Zeng, Huanzhou Xu, Xiang Ren, Yuning Sun","doi":"10.1111/mmi.15263","DOIUrl":"https://doi.org/10.1111/mmi.15263","url":null,"abstract":"Minute virus of canines (MVC) belongs to the genus <jats:italic>Bocaparvovirus</jats:italic> (formerly <jats:italic>Bocavirus</jats:italic>) within the <jats:italic>Parvoviridae</jats:italic> family and causes serious respiratory and gastrointestinal symptoms in neonatal canines worldwide. A productive viral infection relies on the successful recruitment of host factors for various stages of the viral life cycle. However, little is known about the MVC‐host cell interactions. In this study, we identified that two cellular proteins (Hsc70 and Hsp70) interacted with NS1 and VP2 proteins of MVC, and both two domains of Hsc70/Hsp70 were mediated for their interactions. Functional studies revealed that Hsp70 was induced by MVC infection, knockdown of Hsc70 considerably suppressed MVC replication, whereas the replication was dramatically promoted by Hsp70 knockdown. It is interesting that low amounts of overexpressed Hsp70 enhanced viral protein expression and virus production, but high amounts of Hsp70 overexpression weakened them. Upon Hsp70 overexpressing, we observed that the ubiquitination of viral proteins changed with Hsp70 overexpression, and proteasome inhibitor (MG132) restored an accumulation of viral proteins. In addition, we verified that Hsp70 family inhibitors remarkably decreased MVC replication. Overall, we identified Hsc70 and Hsp70 as interactors of MVC NS1 and VP2 proteins and were involved in MVC replication, which may provide novel targets for anti‐MVC approach.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":null,"pages":null},"PeriodicalIF":3.6,"publicationDate":"2024-04-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140607944","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}
Microbiotas are complex microbial communities that colonize specific niches in the host and provide essential organismal functions that are important in health and disease. Understanding the ability of each distinct community member to promote or impair host health, alone or in the context of the community, is imperative for understanding how differences in community structure affect host health and vice versa. Recently, a reference 12-member microbiota for the model organism Caenorhabditis elegans, known as CeMbio, was defined. Here, we show the differential ability of each CeMbio bacterial species to activate innate immunity through the conserved PMK-1/p38 MAPK, ACh-WNT, and HLH-30/TFEB pathways. Although distinct CeMbio members differed in their ability to activate the PMK-1/p38 pathway, the ability to do so did not correlate with bacterial-induced lifespan reduction in wild-type or immunodeficient animals. In contrast, most species activated HLH-30/TFEB and showed virulence toward hlh-30-deficient animals. These results suggest that the microbiota of C. elegans is rife with bacteria that can shorten the host's lifespan if host defense is compromised and that HLH-30/TFEB is a fundamental and key host protective factor.
{"title":"Distinct members of the Caenorhabditis elegans CeMbio reference microbiota exert cryptic virulence that is masked by host defense","authors":"Xavier Gonzalez, Javier E. Irazoqui","doi":"10.1111/mmi.15258","DOIUrl":"https://doi.org/10.1111/mmi.15258","url":null,"abstract":"Microbiotas are complex microbial communities that colonize specific niches in the host and provide essential organismal functions that are important in health and disease. Understanding the ability of each distinct community member to promote or impair host health, alone or in the context of the community, is imperative for understanding how differences in community structure affect host health and vice versa. Recently, a reference 12-member microbiota for the model organism <i>Caenorhabditis elegans</i>, known as CeMbio, was defined. Here, we show the differential ability of each CeMbio bacterial species to activate innate immunity through the conserved PMK-1/p38 MAPK, ACh-WNT, and HLH-30/TFEB pathways. Although distinct CeMbio members differed in their ability to activate the PMK-1/p38 pathway, the ability to do so did not correlate with bacterial-induced lifespan reduction in wild-type or immunodeficient animals. In contrast, most species activated HLH-30/TFEB and showed virulence toward <i>hlh-30-</i>deficient animals. These results suggest that the microbiota of <i>C. elegans</i> is rife with bacteria that can shorten the host's lifespan if host defense is compromised and that HLH-30/TFEB is a fundamental and key host protective factor.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":null,"pages":null},"PeriodicalIF":3.6,"publicationDate":"2024-04-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140556767","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}
Corinne von Känel, Silke Oeljeklaus, Christoph Wenger, Philip Stettler, Anke Harsman, Bettina Warscheid, André Schneider
All mitochondria import >95% of their proteins from the cytosol. This process is mediated by protein translocases in the mitochondrial membranes, whose subunits are generally highly conserved. Most eukaryotes have two inner membrane protein translocases (TIMs) that are specialized to import either presequence-containing or mitochondrial carrier proteins. In contrast, the parasitic protozoan Trypanosoma brucei has a single TIM complex consisting of one conserved and five unique subunits. Here, we identify candidates for new subunits of the TIM or the presequence translocase-associated motor (PAM) using a protein–protein interaction network of previously characterized TIM and PAM subunits. This analysis reveals that the trypanosomal TIM complex contains an additional trypanosomatid-specific subunit, designated TbTim15. TbTim15 is associated with the TIM complex, lacks transmembrane domains, and localizes to the intermembrane space. TbTim15 is essential for procyclic and bloodstream forms of trypanosomes. It contains two twin CX9C motifs and mediates import of both presequence-containing and mitochondrial carrier proteins. While the precise function of TbTim15 in mitochondrial protein import is unknown, our results are consistent with the notion that it may function as an import receptor for the non-canonical trypanosomal TIM complex.
所有线粒体都从细胞质中输入 95% 的蛋白质。这一过程由线粒体膜上的蛋白质转运酶介导，其亚基通常高度保守。大多数真核生物都有两种内膜蛋白转运酶（TIMs），专门用于导入含前序蛋白或线粒体载体蛋白。相比之下，寄生原生动物布氏锥虫只有一个由一个保守亚基和五个独特亚基组成的 TIM 复合物。在这里，我们利用先前表征过的 TIM 和 PAM 亚基的蛋白质-蛋白质相互作用网络，确定了 TIM 或前序列转运酶相关马达（PAM）新亚基的候选者。这项分析表明，锥虫 TIM 复合物包含一个额外的锥虫特异性亚基，命名为 TbTim15。TbTim15 与 TIM 复合物相关，缺乏跨膜结构域，并定位在膜间空间。TbTim15 对原环和血流形式的锥虫至关重要。它含有两个孪生 CX9C 基序，介导含前序和线粒体载体蛋白的导入。虽然 TbTim15 在线粒体蛋白导入中的确切功能尚不清楚，但我们的研究结果与它可能充当非典型锥虫 TIM 复合物的导入受体这一观点是一致的。
{"title":"Intermembrane space-localized TbTim15 is an essential subunit of the single mitochondrial inner membrane protein translocase of trypanosomes","authors":"Corinne von Känel, Silke Oeljeklaus, Christoph Wenger, Philip Stettler, Anke Harsman, Bettina Warscheid, André Schneider","doi":"10.1111/mmi.15262","DOIUrl":"https://doi.org/10.1111/mmi.15262","url":null,"abstract":"All mitochondria import >95% of their proteins from the cytosol. This process is mediated by protein translocases in the mitochondrial membranes, whose subunits are generally highly conserved. Most eukaryotes have two inner membrane protein translocases (TIMs) that are specialized to import either presequence-containing or mitochondrial carrier proteins. In contrast, the parasitic protozoan <i>Trypanosoma brucei</i> has a single TIM complex consisting of one conserved and five unique subunits. Here, we identify candidates for new subunits of the TIM or the presequence translocase-associated motor (PAM) using a protein–protein interaction network of previously characterized TIM and PAM subunits. This analysis reveals that the trypanosomal TIM complex contains an additional trypanosomatid-specific subunit, designated TbTim15. TbTim15 is associated with the TIM complex, lacks transmembrane domains, and localizes to the intermembrane space. TbTim15 is essential for procyclic and bloodstream forms of trypanosomes. It contains two twin CX<sub>9</sub>C motifs and mediates import of both presequence-containing and mitochondrial carrier proteins. While the precise function of TbTim15 in mitochondrial protein import is unknown, our results are consistent with the notion that it may function as an import receptor for the non-canonical trypanosomal TIM complex.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":null,"pages":null},"PeriodicalIF":3.6,"publicationDate":"2024-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140556932","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}
Ilaria Baglivo, Gaetano Malgieri, Roy Martin Roop, Ian S. Barton, Xindan Wang, Veronica Russo, Luciano Pirone, Emilia M. Pedone, Paolo V. Pedone
MucR belongs to a large protein family whose members regulate the expression of virulence and symbiosis genes in α-proteobacteria species. This protein and its homologs were initially studied as classical transcriptional regulators mostly involved in repression of target genes by binding their promoters. Very recent studies have led to the classification of MucR as a new type of Histone-like Nucleoid Structuring (H-NS) protein. Thus this review is an effort to put together a complete and unifying story demonstrating how genetic and biochemical findings on MucR suggested that this protein is not a classical transcriptional regulator, but functions as a novel type of H-NS-like protein, which binds AT-rich regions of genomic DNA and regulates gene expression.
MucR 属于一个庞大的蛋白家族，其成员可调节α-蛋白细菌中毒力和共生基因的表达。这种蛋白质及其同源物最初是作为经典的转录调节因子进行研究的，主要通过结合启动子抑制目标基因。最近的研究将 MucR 归类为一种新型组蛋白样核结构蛋白（H-NS）。因此，这篇综述力图通过一个完整而统一的故事，说明有关 MucR 的遗传和生化研究结果是如何表明这种蛋白不是经典的转录调节因子，而是一种新型的类 H-NS 蛋白，它能结合基因组 DNA 中富含 AT 的区域并调节基因表达。
{"title":"MucR protein: Three decades of studies have led to the identification of a new H-NS-like protein","authors":"Ilaria Baglivo, Gaetano Malgieri, Roy Martin Roop, Ian S. Barton, Xindan Wang, Veronica Russo, Luciano Pirone, Emilia M. Pedone, Paolo V. Pedone","doi":"10.1111/mmi.15261","DOIUrl":"https://doi.org/10.1111/mmi.15261","url":null,"abstract":"MucR belongs to a large protein family whose members regulate the expression of virulence and symbiosis genes in α-proteobacteria species. This protein and its homologs were initially studied as classical transcriptional regulators mostly involved in repression of target genes by binding their promoters. Very recent studies have led to the classification of MucR as a new type of Histone-like Nucleoid Structuring (H-NS) protein. Thus this review is an effort to put together a complete and unifying story demonstrating how genetic and biochemical findings on MucR suggested that this protein is not a classical transcriptional regulator, but functions as a novel type of H-NS-like protein, which binds AT-rich regions of genomic DNA and regulates gene expression.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":null,"pages":null},"PeriodicalIF":3.6,"publicationDate":"2024-04-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140553658","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}
The interplay between bacterial chromosome organization and functions such as transcription and replication can be studied in increasing detail using novel experimental techniques. Interpreting the resulting quantitative data, however, can be theoretically challenging. In this minireview, we discuss how connecting experimental observations to biophysical theory and modeling can give rise to new insights on bacterial chromosome organization. We consider three flavors of models of increasing complexity: simple polymer models that explore how physical constraints, such as confinement or plectoneme branching, can affect bacterial chromosome organization; bottom‐up mechanistic models that connect these constraints to their underlying causes, for instance, chromosome compaction to macromolecular crowding, or supercoiling to transcription; and finally, data‐driven methods for inferring interpretable and quantitative models directly from complex experimental data. Using recent examples, we discuss how biophysical models can both deepen our understanding of how bacterial chromosomes are structured and give rise to novel predictions about bacterial chromosome organization.
{"title":"Physical models of bacterial chromosomes","authors":"Janni Harju, Chase P. Broedersz","doi":"10.1111/mmi.15257","DOIUrl":"https://doi.org/10.1111/mmi.15257","url":null,"abstract":"The interplay between bacterial chromosome organization and functions such as transcription and replication can be studied in increasing detail using novel experimental techniques. Interpreting the resulting quantitative data, however, can be theoretically challenging. In this minireview, we discuss how connecting experimental observations to biophysical theory and modeling can give rise to new insights on bacterial chromosome organization. We consider three flavors of models of increasing complexity: simple polymer models that explore how physical constraints, such as confinement or plectoneme branching, can affect bacterial chromosome organization; bottom‐up mechanistic models that connect these constraints to their underlying causes, for instance, chromosome compaction to macromolecular crowding, or supercoiling to transcription; and finally, data‐driven methods for inferring interpretable and quantitative models directly from complex experimental data. Using recent examples, we discuss how biophysical models can both deepen our understanding of how bacterial chromosomes are structured and give rise to novel predictions about bacterial chromosome organization.","PeriodicalId":19006,"journal":{"name":"Molecular Microbiology","volume":null,"pages":null},"PeriodicalIF":3.6,"publicationDate":"2024-04-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140352198","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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