Pub Date : 2024-08-21DOI: 10.1038/s41594-024-01380-w
Alperen Yilmaz, Gulben Gurhan, Jacob H. Hanna
Two recent studies provide mechanistic insights into how LIN28A controls changes in cell fate identity, focusing on either a let-7-independent or let-7-dependent pathway of action involving LIN28A.
{"title":"Putting together pieces of the LIN28A pathway puzzle","authors":"Alperen Yilmaz, Gulben Gurhan, Jacob H. Hanna","doi":"10.1038/s41594-024-01380-w","DOIUrl":"10.1038/s41594-024-01380-w","url":null,"abstract":"Two recent studies provide mechanistic insights into how LIN28A controls changes in cell fate identity, focusing on either a let-7-independent or let-7-dependent pathway of action involving LIN28A.","PeriodicalId":49141,"journal":{"name":"Nature Structural & Molecular Biology","volume":"31 9","pages":"1313-1314"},"PeriodicalIF":12.5,"publicationDate":"2024-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142013801","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-20DOI: 10.1038/s41594-024-01373-9
Gabriella N. L. Chua, John W. Watters, Paul Dominic B. Olinares, Masuda Begum, Lauren E. Vostal, Joshua A. Luo, Brian T. Chait, Shixin Liu
Methyl-CpG-binding protein 2 (MeCP2) is an essential chromatin-binding protein whose mutations cause Rett syndrome (RTT), a severe neurological disorder that primarily affects young females. The canonical view of MeCP2 as a DNA methylation-dependent transcriptional repressor has proven insufficient to describe its dynamic interaction with chromatin and multifaceted roles in genome organization and gene expression. Here we used single-molecule correlative force and fluorescence microscopy to directly visualize the dynamics of wild-type and RTT-causing mutant MeCP2 on DNA. We discovered that MeCP2 exhibits distinct one-dimensional diffusion kinetics when bound to unmethylated versus CpG methylated DNA, enabling methylation-specific activities such as co-repressor recruitment. We further found that, on chromatinized DNA, MeCP2 preferentially localizes to nucleosomes and stabilizes them from mechanical perturbation. Our results reveal the multimodal behavior of MeCP2 on chromatin that underlies its DNA methylation- and nucleosome-dependent functions and provide a biophysical framework for dissecting the molecular pathology of RTT mutations. Using single-molecule techniques, the authors find that the methyl-CpG-binding protein MeCP2, whose mutations cause Rett syndrome, exhibits distinctive behaviors when bound to nucleosomes versus free DNA, thus directing its multifaceted functions on chromatin.
甲基-CpG结合蛋白2（MeCP2）是一种重要的染色质结合蛋白，其突变会导致雷特综合征（RTT），这是一种主要影响年轻女性的严重神经系统疾病。事实证明，将 MeCP2 视为 DNA 甲基化依赖性转录抑制因子的传统观点不足以描述它与染色质的动态相互作用以及在基因组组织和基因表达中的多方面作用。在这里，我们使用单分子相关力和荧光显微镜直接观察了野生型和RTT致突变体MeCP2在DNA上的动态。我们发现，当 MeCP2 与未甲基化 DNA 和 CpG 甲基化 DNA 结合时，会表现出不同的一维扩散动力学，从而实现甲基化特异性活动，如共抑制因子招募。我们还发现，在染色质化的 DNA 上，MeCP2 会优先定位于核小体，并使其免受机械扰动。我们的研究结果揭示了MeCP2在染色质上的多模式行为，这种行为是其DNA甲基化和核糖体依赖性功能的基础，并为剖析RTT突变的分子病理学提供了一个生物物理框架。
{"title":"Differential dynamics specify MeCP2 function at nucleosomes and methylated DNA","authors":"Gabriella N. L. Chua, John W. Watters, Paul Dominic B. Olinares, Masuda Begum, Lauren E. Vostal, Joshua A. Luo, Brian T. Chait, Shixin Liu","doi":"10.1038/s41594-024-01373-9","DOIUrl":"10.1038/s41594-024-01373-9","url":null,"abstract":"Methyl-CpG-binding protein 2 (MeCP2) is an essential chromatin-binding protein whose mutations cause Rett syndrome (RTT), a severe neurological disorder that primarily affects young females. The canonical view of MeCP2 as a DNA methylation-dependent transcriptional repressor has proven insufficient to describe its dynamic interaction with chromatin and multifaceted roles in genome organization and gene expression. Here we used single-molecule correlative force and fluorescence microscopy to directly visualize the dynamics of wild-type and RTT-causing mutant MeCP2 on DNA. We discovered that MeCP2 exhibits distinct one-dimensional diffusion kinetics when bound to unmethylated versus CpG methylated DNA, enabling methylation-specific activities such as co-repressor recruitment. We further found that, on chromatinized DNA, MeCP2 preferentially localizes to nucleosomes and stabilizes them from mechanical perturbation. Our results reveal the multimodal behavior of MeCP2 on chromatin that underlies its DNA methylation- and nucleosome-dependent functions and provide a biophysical framework for dissecting the molecular pathology of RTT mutations. Using single-molecule techniques, the authors find that the methyl-CpG-binding protein MeCP2, whose mutations cause Rett syndrome, exhibits distinctive behaviors when bound to nucleosomes versus free DNA, thus directing its multifaceted functions on chromatin.","PeriodicalId":49141,"journal":{"name":"Nature Structural & Molecular Biology","volume":"31 11","pages":"1789-1797"},"PeriodicalIF":12.5,"publicationDate":"2024-08-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41594-024-01373-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142007534","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-13DOI: 10.1038/s41594-024-01371-x
The extracellular AMPA receptor N-terminal domain (NTD) affects synaptic strength by tuning receptor diffusion. We reveal that pH fluctuations accompanying synaptic activity alter NTD conformation of the functionally dominant GluA2 subunit, via proton sensing by an NTD histidine residue, thereby increasing gating kinetics and receptor diffusion at the synapse.
{"title":"How protons shape AMPA receptor structure, function and diffusion at the synapse","authors":"","doi":"10.1038/s41594-024-01371-x","DOIUrl":"10.1038/s41594-024-01371-x","url":null,"abstract":"The extracellular AMPA receptor N-terminal domain (NTD) affects synaptic strength by tuning receptor diffusion. We reveal that pH fluctuations accompanying synaptic activity alter NTD conformation of the functionally dominant GluA2 subunit, via proton sensing by an NTD histidine residue, thereby increasing gating kinetics and receptor diffusion at the synapse.","PeriodicalId":49141,"journal":{"name":"Nature Structural & Molecular Biology","volume":"31 10","pages":"1466-1467"},"PeriodicalIF":12.5,"publicationDate":"2024-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141973777","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-13DOI: 10.1038/s41594-024-01369-5
Josip Ivica, Nejc Kejzar, Hinze Ho, Imogen Stockwell, Viktor Kuchtiak, Alexander M. Scrutton, Terunaga Nakagawa, Ingo H. Greger
AMPA glutamate receptors (AMPARs) are ion channel tetramers that mediate the majority of fast excitatory synaptic transmission. They are composed of four subunits (GluA1–GluA4); the GluA2 subunit dominates AMPAR function throughout the forebrain. Its extracellular N-terminal domain (NTD) determines receptor localization at the synapse, ensuring reliable synaptic transmission and plasticity. This synaptic anchoring function requires a compact NTD tier, stabilized by a GluA2-specific NTD interface. Here we show that low pH conditions, which accompany synaptic activity, rupture this interface. All-atom molecular dynamics simulations reveal that protonation of an interfacial histidine residue (H208) centrally contributes to NTD rearrangement. Moreover, in stark contrast to their canonical compact arrangement at neutral pH, GluA2 cryo-electron microscopy structures exhibit a wide spectrum of NTD conformations under acidic conditions. We show that the consequences of this pH-dependent conformational control are twofold: rupture of the NTD tier slows recovery from desensitized states and increases receptor mobility at mouse hippocampal synapses. Therefore, a proton-triggered NTD switch will shape both AMPAR location and kinetics, thereby impacting synaptic signal transmission. Combining patch-clamp electrophysiology, molecular dynamics simulations, cryo-electron microscopy and imaging of neuronal synapses, the authors reveal how AMPA glutamate receptors are regulated by protons that are released from synaptic vesicles during signal transmission.
{"title":"Proton-triggered rearrangement of the AMPA receptor N-terminal domains impacts receptor kinetics and synaptic localization","authors":"Josip Ivica, Nejc Kejzar, Hinze Ho, Imogen Stockwell, Viktor Kuchtiak, Alexander M. Scrutton, Terunaga Nakagawa, Ingo H. Greger","doi":"10.1038/s41594-024-01369-5","DOIUrl":"10.1038/s41594-024-01369-5","url":null,"abstract":"AMPA glutamate receptors (AMPARs) are ion channel tetramers that mediate the majority of fast excitatory synaptic transmission. They are composed of four subunits (GluA1–GluA4); the GluA2 subunit dominates AMPAR function throughout the forebrain. Its extracellular N-terminal domain (NTD) determines receptor localization at the synapse, ensuring reliable synaptic transmission and plasticity. This synaptic anchoring function requires a compact NTD tier, stabilized by a GluA2-specific NTD interface. Here we show that low pH conditions, which accompany synaptic activity, rupture this interface. All-atom molecular dynamics simulations reveal that protonation of an interfacial histidine residue (H208) centrally contributes to NTD rearrangement. Moreover, in stark contrast to their canonical compact arrangement at neutral pH, GluA2 cryo-electron microscopy structures exhibit a wide spectrum of NTD conformations under acidic conditions. We show that the consequences of this pH-dependent conformational control are twofold: rupture of the NTD tier slows recovery from desensitized states and increases receptor mobility at mouse hippocampal synapses. Therefore, a proton-triggered NTD switch will shape both AMPAR location and kinetics, thereby impacting synaptic signal transmission. Combining patch-clamp electrophysiology, molecular dynamics simulations, cryo-electron microscopy and imaging of neuronal synapses, the authors reveal how AMPA glutamate receptors are regulated by protons that are released from synaptic vesicles during signal transmission.","PeriodicalId":49141,"journal":{"name":"Nature Structural & Molecular Biology","volume":"31 10","pages":"1601-1613"},"PeriodicalIF":12.5,"publicationDate":"2024-08-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41594-024-01369-5.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141973779","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-08-09DOI: 10.1038/s41594-024-01362-y
Michael C. Owens, Amber Yanas, Kathy Fange Liu
The complexity of biological sex differences is markedly evident in human physiology and pathology. Although many of these differences can be ascribed to the expression of sex hormones, another contributor to sex differences lies in the sex chromosomes beyond their role in sex determination. Although largely nonhomologous, the human sex chromosomes express seventeen pairs of homologous genes, referred to as the ‘X–Y pairs.’ The X chromosome-encoded homologs of these Y-encoded proteins are crucial players in several cellular processes, and their dysregulation frequently results in disease development. Many diseases related to these X-encoded homologs present with sex-biased incidence or severity. By contrast, comparatively little is known about the differential functions of the Y-linked homologs. Here, we summarize and discuss the current understanding of five of these X–Y paired proteins, with recent evidence of differential functions and of having a potential link to sex biases in disease, highlighting how amino acid-level sequence differences may differentiate their functions and contribute to sex biases in human disease. Here, the authors examine and discuss the functional complexity and cellular implications of X–Y pairs, homologous genes expressed in the human sex chromosomes.
生物性别差异的复杂性在人类生理学和病理学中显而易见。虽然其中许多差异可归因于性激素的表达，但性别差异的另一个原因在于性染色体在性别决定中的作用。人类的性染色体虽然在很大程度上是非同源的，但它表达了 17 对同源基因，被称为 "X-Y 对"。这些 Y 编码蛋白的 X 染色体编码同源物在多个细胞过程中起着至关重要的作用，它们的失调经常导致疾病的发生。许多与这些 X 染色体编码同源物相关的疾病在发病率或严重程度上都存在性别差异。相比之下，人们对 Y 连锁同源物的不同功能知之甚少。在这里，我们总结并讨论了目前对其中五种 X-Y 配对蛋白的认识，这些蛋白最近有证据表明它们具有不同的功能，并与疾病中的性别偏见有潜在的联系，我们将重点介绍氨基酸水平的序列差异可能如何区分它们的功能并导致人类疾病中的性别偏见。
{"title":"Sex chromosome-encoded protein homologs: current progress and open questions","authors":"Michael C. Owens, Amber Yanas, Kathy Fange Liu","doi":"10.1038/s41594-024-01362-y","DOIUrl":"10.1038/s41594-024-01362-y","url":null,"abstract":"The complexity of biological sex differences is markedly evident in human physiology and pathology. Although many of these differences can be ascribed to the expression of sex hormones, another contributor to sex differences lies in the sex chromosomes beyond their role in sex determination. Although largely nonhomologous, the human sex chromosomes express seventeen pairs of homologous genes, referred to as the ‘X–Y pairs.’ The X chromosome-encoded homologs of these Y-encoded proteins are crucial players in several cellular processes, and their dysregulation frequently results in disease development. Many diseases related to these X-encoded homologs present with sex-biased incidence or severity. By contrast, comparatively little is known about the differential functions of the Y-linked homologs. Here, we summarize and discuss the current understanding of five of these X–Y paired proteins, with recent evidence of differential functions and of having a potential link to sex biases in disease, highlighting how amino acid-level sequence differences may differentiate their functions and contribute to sex biases in human disease. Here, the authors examine and discuss the functional complexity and cellular implications of X–Y pairs, homologous genes expressed in the human sex chromosomes.","PeriodicalId":49141,"journal":{"name":"Nature Structural & Molecular Biology","volume":"31 8","pages":"1156-1166"},"PeriodicalIF":12.5,"publicationDate":"2024-08-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141908894","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-30DOI: 10.1038/s41594-024-01368-6
Kelli L. Hvorecny
Snowflakes, seashells and Romanesco broccoli are striking examples of fractal geometries in nature. A recent study published in Nature defines a set of molecular mechanisms for fractal assembly by identifying a nanometer-scale, regular fractal assembled from a native protein found in blue-green algae that likely arose as an evolutionary accident.
{"title":"Identifying nature’s smallest fractals","authors":"Kelli L. Hvorecny","doi":"10.1038/s41594-024-01368-6","DOIUrl":"10.1038/s41594-024-01368-6","url":null,"abstract":"Snowflakes, seashells and Romanesco broccoli are striking examples of fractal geometries in nature. A recent study published in Nature defines a set of molecular mechanisms for fractal assembly by identifying a nanometer-scale, regular fractal assembled from a native protein found in blue-green algae that likely arose as an evolutionary accident.","PeriodicalId":49141,"journal":{"name":"Nature Structural & Molecular Biology","volume":"31 8","pages":"1147-1149"},"PeriodicalIF":12.5,"publicationDate":"2024-07-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141794520","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-25DOI: 10.1038/s41594-024-01363-x
Miha Modic, Klara Kuret, Sebastian Steinhauser, Rupert Faraway, Emiel van Genderen, Igor Ruiz de Los Mozos, Jona Novljan, Žiga Vičič, Flora C. Y. Lee, Derk ten Berge, Nicholas M. Luscombe, Jernej Ule
Signaling pathways drive cell fate transitions largely by changing gene expression. However, the mechanisms for rapid and selective transcriptome rewiring in response to signaling cues remain elusive. Here we use deep learning to deconvolve both the sequence determinants and the trans-acting regulators that trigger extracellular signal-regulated kinase (ERK)–mitogen-activated protein kinase kinase (MEK)-induced decay of the naive pluripotency mRNAs. Timing of decay is coupled to embryo implantation through ERK–MEK phosphorylation of LIN28A, which repositions pLIN28A to the highly A+U-rich 3′ untranslated region (3′UTR) termini of naive pluripotency mRNAs. Interestingly, these A+U-rich 3′UTR termini serve as poly(A)-binding protein (PABP)-binding hubs, poised for signal-induced convergence with LIN28A. The multivalency of AUU motifs determines the efficacy of pLIN28A–PABP convergence, which enhances PABP 3′UTR binding, decreases the protection of poly(A) tails and activates mRNA decay to enable progression toward primed pluripotency. Thus, the signal-induced convergence of LIN28A with PABP–RNA hubs drives the rapid selection of naive mRNAs for decay, enabling the transcriptome remodeling that ensures swift developmental progression. Here the authors show that, upon embryo implantation, signaling triggers a large-scale rearrangement of protein–RNA interactions. Phosphorylated LIN28A reassembles onto the 3′ untranslated region termini of pluripotency-associated mRNAs, where it converges with the binding of poly(A)-binding protein and drives selective mRNA decay.
{"title":"Poised PABP–RNA hubs implement signal-dependent mRNA decay in development","authors":"Miha Modic, Klara Kuret, Sebastian Steinhauser, Rupert Faraway, Emiel van Genderen, Igor Ruiz de Los Mozos, Jona Novljan, Žiga Vičič, Flora C. Y. Lee, Derk ten Berge, Nicholas M. Luscombe, Jernej Ule","doi":"10.1038/s41594-024-01363-x","DOIUrl":"10.1038/s41594-024-01363-x","url":null,"abstract":"Signaling pathways drive cell fate transitions largely by changing gene expression. However, the mechanisms for rapid and selective transcriptome rewiring in response to signaling cues remain elusive. Here we use deep learning to deconvolve both the sequence determinants and the trans-acting regulators that trigger extracellular signal-regulated kinase (ERK)–mitogen-activated protein kinase kinase (MEK)-induced decay of the naive pluripotency mRNAs. Timing of decay is coupled to embryo implantation through ERK–MEK phosphorylation of LIN28A, which repositions pLIN28A to the highly A+U-rich 3′ untranslated region (3′UTR) termini of naive pluripotency mRNAs. Interestingly, these A+U-rich 3′UTR termini serve as poly(A)-binding protein (PABP)-binding hubs, poised for signal-induced convergence with LIN28A. The multivalency of AUU motifs determines the efficacy of pLIN28A–PABP convergence, which enhances PABP 3′UTR binding, decreases the protection of poly(A) tails and activates mRNA decay to enable progression toward primed pluripotency. Thus, the signal-induced convergence of LIN28A with PABP–RNA hubs drives the rapid selection of naive mRNAs for decay, enabling the transcriptome remodeling that ensures swift developmental progression. Here the authors show that, upon embryo implantation, signaling triggers a large-scale rearrangement of protein–RNA interactions. Phosphorylated LIN28A reassembles onto the 3′ untranslated region termini of pluripotency-associated mRNAs, where it converges with the binding of poly(A)-binding protein and drives selective mRNA decay.","PeriodicalId":49141,"journal":{"name":"Nature Structural & Molecular Biology","volume":"31 9","pages":"1439-1447"},"PeriodicalIF":12.5,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41594-024-01363-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141759830","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-25DOI: 10.1038/s41594-024-01357-9
Gangshun Yi, Mingda Ye, Loic Carrique, Afaf El-Sagheer, Tom Brown, Chris J. Norbury, Peijun Zhang, Robert J. C. Gilbert
Tumor-suppressor let-7 pre-microRNAs (miRNAs) are regulated by terminal uridylyltransferases TUT7 and TUT4 that either promote let-7 maturation by adding a single uridine nucleotide to the pre-miRNA 3′ end or mark them for degradation by the addition of multiple uridines. Oligo-uridylation is increased in cells by enhanced TUT7/4 expression and especially by the RNA-binding pluripotency factor LIN28A. Using cryogenic electron microscopy, we captured high-resolution structures of active forms of TUT7 alone, of TUT7 plus pre-miRNA and of both TUT7 and TUT4 bound with pre-miRNA and LIN28A. Our structures reveal that pre-miRNAs engage the enzymes in fundamentally different ways depending on the presence of LIN28A, which clamps them onto the TUTs to enable processive 3′ oligo-uridylation. This study reveals the molecular basis for mono- versus oligo-uridylation by TUT7/4, as determined by the presence of LIN28A, and thus their mechanism of action in the regulation of cell fate and in cancer. Here, the authors show that cytoplasmic uridylyltransferases TUT7 and TUT4 bind let-7 pre-miRNA by alternative means in the absence and presence of Lin28A, which directly interacts with both RNA and enzyme to convert from a distributive to a processive mode of action.
{"title":"Structural basis for activity switching in polymerases determining the fate of let-7 pre-miRNAs","authors":"Gangshun Yi, Mingda Ye, Loic Carrique, Afaf El-Sagheer, Tom Brown, Chris J. Norbury, Peijun Zhang, Robert J. C. Gilbert","doi":"10.1038/s41594-024-01357-9","DOIUrl":"10.1038/s41594-024-01357-9","url":null,"abstract":"Tumor-suppressor let-7 pre-microRNAs (miRNAs) are regulated by terminal uridylyltransferases TUT7 and TUT4 that either promote let-7 maturation by adding a single uridine nucleotide to the pre-miRNA 3′ end or mark them for degradation by the addition of multiple uridines. Oligo-uridylation is increased in cells by enhanced TUT7/4 expression and especially by the RNA-binding pluripotency factor LIN28A. Using cryogenic electron microscopy, we captured high-resolution structures of active forms of TUT7 alone, of TUT7 plus pre-miRNA and of both TUT7 and TUT4 bound with pre-miRNA and LIN28A. Our structures reveal that pre-miRNAs engage the enzymes in fundamentally different ways depending on the presence of LIN28A, which clamps them onto the TUTs to enable processive 3′ oligo-uridylation. This study reveals the molecular basis for mono- versus oligo-uridylation by TUT7/4, as determined by the presence of LIN28A, and thus their mechanism of action in the regulation of cell fate and in cancer. Here, the authors show that cytoplasmic uridylyltransferases TUT7 and TUT4 bind let-7 pre-miRNA by alternative means in the absence and presence of Lin28A, which directly interacts with both RNA and enzyme to convert from a distributive to a processive mode of action.","PeriodicalId":49141,"journal":{"name":"Nature Structural & Molecular Biology","volume":"31 9","pages":"1426-1438"},"PeriodicalIF":12.5,"publicationDate":"2024-07-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41594-024-01357-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141759831","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-22DOI: 10.1038/s41594-024-01348-w
Victor R. A. Dubach, Pablo San Segundo-Acosta, Bonnie J. Murphy
Nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (NOXs) have a major role in the physiology of eukaryotic cells by mediating reactive oxygen species production. Evolutionarily distant proteins with the NOX catalytic core have been found in bacteria, including Streptococcus pneumoniae NOX (SpNOX), which is proposed as a model for studying NOXs because of its high activity and stability in detergent micelles. We present here cryo-electron microscopy structures of substrate-free and nicotinamide adenine dinucleotide (NADH)-bound SpNOX and of NADPH-bound wild-type and F397A SpNOX under turnover conditions. These high-resolution structures provide insights into the electron-transfer pathway and reveal a hydride-transfer mechanism regulated by the displacement of F397. We conducted structure-guided mutagenesis and biochemical analyses that explain the absence of substrate specificity toward NADPH and suggest the mechanism behind constitutive activity. Our study presents the structural basis underlying SpNOX enzymatic activity and sheds light on its potential in vivo function. Using cryo-electron microscopy, the authors obtained structures of Streptococcus pneumoniae nicotinamide adenine dinucleotide phosphate (NADPH) oxidase in different states. Combined with site-directed mutagenesis and biochemical assays, the structures shed light on the activity and regulation of NADPH oxidases.
{"title":"Structural and mechanistic insights into Streptococcus pneumoniae NADPH oxidase","authors":"Victor R. A. Dubach, Pablo San Segundo-Acosta, Bonnie J. Murphy","doi":"10.1038/s41594-024-01348-w","DOIUrl":"10.1038/s41594-024-01348-w","url":null,"abstract":"Nicotinamide adenine dinucleotide phosphate (NADPH) oxidases (NOXs) have a major role in the physiology of eukaryotic cells by mediating reactive oxygen species production. Evolutionarily distant proteins with the NOX catalytic core have been found in bacteria, including Streptococcus pneumoniae NOX (SpNOX), which is proposed as a model for studying NOXs because of its high activity and stability in detergent micelles. We present here cryo-electron microscopy structures of substrate-free and nicotinamide adenine dinucleotide (NADH)-bound SpNOX and of NADPH-bound wild-type and F397A SpNOX under turnover conditions. These high-resolution structures provide insights into the electron-transfer pathway and reveal a hydride-transfer mechanism regulated by the displacement of F397. We conducted structure-guided mutagenesis and biochemical analyses that explain the absence of substrate specificity toward NADPH and suggest the mechanism behind constitutive activity. Our study presents the structural basis underlying SpNOX enzymatic activity and sheds light on its potential in vivo function. Using cryo-electron microscopy, the authors obtained structures of Streptococcus pneumoniae nicotinamide adenine dinucleotide phosphate (NADPH) oxidase in different states. Combined with site-directed mutagenesis and biochemical assays, the structures shed light on the activity and regulation of NADPH oxidases.","PeriodicalId":49141,"journal":{"name":"Nature Structural & Molecular Biology","volume":"31 11","pages":"1769-1777"},"PeriodicalIF":12.5,"publicationDate":"2024-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41594-024-01348-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141737018","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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