Pub Date : 2024-08-08DOI: 10.1038/s41594-024-01372-w
Vadim Molodtsov, Chengyuan Wang, Jing Zhang, Jason T. Kaelber, Gregor Blaha, Richard H. Ebright
The NusG paralog RfaH mediates bacterial transcription–translation coupling in genes that contain a DNA sequence element, termed an ops site, required for pausing RNA polymerase (RNAP) and for loading RfaH onto the paused RNAP. Here, we report cryo-electron microscopy structures of transcription–translation complexes (TTCs) containing Escherichia coli RfaH. The results show that RfaH bridges RNAP and the ribosome, with the RfaH N-terminal domain interacting with RNAP and the RfaH C-terminal domain interacting with the ribosome. The results show that the distribution of translational and orientational positions of RNAP relative to the ribosome in RfaH-coupled TTCs is more restricted than in NusG-coupled TTCs because of the more restricted flexibility of the RfaH interdomain linker. The results further suggest that the structural organization of RfaH-coupled TTCs in the ‘loading state’, in which RNAP and RfaH are located at the ops site during formation of the TTC, is the same as the structural organization of RfaH-coupled TTCs in the ‘loaded state’, in which RNAP and RfaH are located at positions downstream of the ops site during function of the TTC. The results define the structural organization of RfaH-containing TTCs and set the stage for analysis of functions of RfaH during translation initiation and transcription–translation coupling. Here, the authors report cryo-electron microscopy structures of Escherichia coli transcription–translation complexes containing the transcription–translation coupling factor RfaH, showing that RfaH physically bridges RNA polymerase and the ribosome.
{"title":"Structural basis of RfaH-mediated transcription–translation coupling","authors":"Vadim Molodtsov, Chengyuan Wang, Jing Zhang, Jason T. Kaelber, Gregor Blaha, Richard H. Ebright","doi":"10.1038/s41594-024-01372-w","DOIUrl":"10.1038/s41594-024-01372-w","url":null,"abstract":"The NusG paralog RfaH mediates bacterial transcription–translation coupling in genes that contain a DNA sequence element, termed an ops site, required for pausing RNA polymerase (RNAP) and for loading RfaH onto the paused RNAP. Here, we report cryo-electron microscopy structures of transcription–translation complexes (TTCs) containing Escherichia coli RfaH. The results show that RfaH bridges RNAP and the ribosome, with the RfaH N-terminal domain interacting with RNAP and the RfaH C-terminal domain interacting with the ribosome. The results show that the distribution of translational and orientational positions of RNAP relative to the ribosome in RfaH-coupled TTCs is more restricted than in NusG-coupled TTCs because of the more restricted flexibility of the RfaH interdomain linker. The results further suggest that the structural organization of RfaH-coupled TTCs in the ‘loading state’, in which RNAP and RfaH are located at the ops site during formation of the TTC, is the same as the structural organization of RfaH-coupled TTCs in the ‘loaded state’, in which RNAP and RfaH are located at positions downstream of the ops site during function of the TTC. The results define the structural organization of RfaH-containing TTCs and set the stage for analysis of functions of RfaH during translation initiation and transcription–translation coupling. Here, the authors report cryo-electron microscopy structures of Escherichia coli transcription–translation complexes containing the transcription–translation coupling factor RfaH, showing that RfaH physically bridges RNA polymerase and the ribosome.","PeriodicalId":49141,"journal":{"name":"Nature Structural & Molecular Biology","volume":"31 12","pages":"1932-1941"},"PeriodicalIF":12.5,"publicationDate":"2024-08-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141904613","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 : 2024-08-07DOI: 10.1038/s41594-024-01370-y
Johann J. Roske, Joseph T. P. Yeeles
During chromosome replication, the nascent leading strand is synthesized by DNA polymerase epsilon (Pol ε), which associates with the sliding clamp processivity factor proliferating cell nuclear antigen (PCNA) to form a processive holoenzyme. For high-fidelity DNA synthesis, Pol ε relies on nucleotide selectivity and its proofreading ability to detect and excise a misincorporated nucleotide. Here, we present cryo-electron microscopy (cryo-EM) structures of human Pol ε in complex with PCNA, DNA and an incoming nucleotide, revealing how Pol ε associates with PCNA through its PCNA-interacting peptide box and additional unique features of its catalytic domain. Furthermore, by solving a series of cryo-EM structures of Pol ε at a mismatch-containing DNA, we elucidate how Pol ε senses and edits a misincorporated nucleotide. Our structures delineate steps along an intramolecular switching mechanism between polymerase and exonuclease activities, providing the basis for a proofreading mechanism in B-family replicative polymerases. Using cryo-electron microscopy, the authors deepen our mechanistic understanding of nascent leading-strand synthesis during human DNA replication and provide the basis for a proofreading mechanism in B-family replicative polymerases.
在染色体复制过程中，新生前导链由 DNA 聚合酶ε（Pol ε）合成，它与滑动钳加工因子增殖细胞核抗原（PCNA）结合形成一个加工全酶。Pol ε依靠核苷酸选择性及其校对能力来检测和切除错误结合的核苷酸，从而实现高保真的DNA合成。在这里，我们展示了人Pol ε与PCNA、DNA和输入核苷酸复合物的冷冻电子显微镜（cryo-EM）结构，揭示了Pol ε如何通过其PCNA-interacting肽盒与PCNA结合，以及其催化结构域的其他独特特征。此外，通过解决 Pol ε 在含错配 DNA 上的一系列低温电子显微镜结构，我们阐明了 Pol ε 如何感知和编辑误入的核苷酸。我们的结构描述了聚合酶和外切酶活性之间分子内切换机制的步骤，为 B-家族复制聚合酶的校对机制提供了基础。
{"title":"Structural basis for processive daughter-strand synthesis and proofreading by the human leading-strand DNA polymerase Pol ε","authors":"Johann J. Roske, Joseph T. P. Yeeles","doi":"10.1038/s41594-024-01370-y","DOIUrl":"10.1038/s41594-024-01370-y","url":null,"abstract":"During chromosome replication, the nascent leading strand is synthesized by DNA polymerase epsilon (Pol ε), which associates with the sliding clamp processivity factor proliferating cell nuclear antigen (PCNA) to form a processive holoenzyme. For high-fidelity DNA synthesis, Pol ε relies on nucleotide selectivity and its proofreading ability to detect and excise a misincorporated nucleotide. Here, we present cryo-electron microscopy (cryo-EM) structures of human Pol ε in complex with PCNA, DNA and an incoming nucleotide, revealing how Pol ε associates with PCNA through its PCNA-interacting peptide box and additional unique features of its catalytic domain. Furthermore, by solving a series of cryo-EM structures of Pol ε at a mismatch-containing DNA, we elucidate how Pol ε senses and edits a misincorporated nucleotide. Our structures delineate steps along an intramolecular switching mechanism between polymerase and exonuclease activities, providing the basis for a proofreading mechanism in B-family replicative polymerases. Using cryo-electron microscopy, the authors deepen our mechanistic understanding of nascent leading-strand synthesis during human DNA replication and provide the basis for a proofreading mechanism in B-family replicative polymerases.","PeriodicalId":49141,"journal":{"name":"Nature Structural & Molecular Biology","volume":"31 12","pages":"1921-1931"},"PeriodicalIF":12.5,"publicationDate":"2024-08-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41594-024-01370-y.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141899782","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 : 2024-07-30DOI: 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 : 2024-07-24DOI: 10.1038/s41594-024-01353-z
Michael C. Lanz, Shuyuan Zhang, Matthew P. Swaffer, Inbal Ziv, Luisa Hernández Götz, Jacob Kim, Frank McCarthy, Daniel F. Jarosz, Joshua E. Elias, Jan M. Skotheim
Cell size is tightly controlled in healthy tissues and single-celled organisms, but it remains unclear how cell size influences physiology. Increasing cell size was recently shown to remodel the proteomes of cultured human cells, demonstrating that large and small cells of the same type can be compositionally different. In the present study, we utilize the natural heterogeneity of hepatocyte ploidy and yeast genetics to establish that the ploidy-to-cell size ratio is a highly conserved determinant of proteome composition. In both mammalian and yeast cells, genome dilution by cell growth elicits a starvation-like phenotype, suggesting that growth in large cells is restricted by genome concentration in a manner that mimics a limiting nutrient. Moreover, genome dilution explains some proteomic changes ascribed to yeast aging. Overall, our data indicate that genome concentration drives changes in cell composition independently of external environmental cues. Here the authors establish that ploidy-to-cell size ratio is a highly conserved determinant of proteome composition. In both mammals and yeast, they find that growth in large cells is restricted by genome concentration as if it were a limiting nutrient.
{"title":"Genome dilution by cell growth drives starvation-like proteome remodeling in mammalian and yeast cells","authors":"Michael C. Lanz, Shuyuan Zhang, Matthew P. Swaffer, Inbal Ziv, Luisa Hernández Götz, Jacob Kim, Frank McCarthy, Daniel F. Jarosz, Joshua E. Elias, Jan M. Skotheim","doi":"10.1038/s41594-024-01353-z","DOIUrl":"10.1038/s41594-024-01353-z","url":null,"abstract":"Cell size is tightly controlled in healthy tissues and single-celled organisms, but it remains unclear how cell size influences physiology. Increasing cell size was recently shown to remodel the proteomes of cultured human cells, demonstrating that large and small cells of the same type can be compositionally different. In the present study, we utilize the natural heterogeneity of hepatocyte ploidy and yeast genetics to establish that the ploidy-to-cell size ratio is a highly conserved determinant of proteome composition. In both mammalian and yeast cells, genome dilution by cell growth elicits a starvation-like phenotype, suggesting that growth in large cells is restricted by genome concentration in a manner that mimics a limiting nutrient. Moreover, genome dilution explains some proteomic changes ascribed to yeast aging. Overall, our data indicate that genome concentration drives changes in cell composition independently of external environmental cues. Here the authors establish that ploidy-to-cell size ratio is a highly conserved determinant of proteome composition. In both mammals and yeast, they find that growth in large cells is restricted by genome concentration as if it were a limiting nutrient.","PeriodicalId":49141,"journal":{"name":"Nature Structural & Molecular Biology","volume":"31 12","pages":"1859-1871"},"PeriodicalIF":12.5,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141755099","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 : 2024-07-22DOI: 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}
Pub Date : 2024-07-19DOI: 10.1038/s41594-024-01360-0
Li Li, Mariia Yu. Rybak, Jinzhong Lin, Matthieu G. Gagnon
Translation termination involves release factors RF1, RF2 and the GTPase RF3 that recycles RF1 and RF2 from the ribosome. RF3 dissociates from the ribosome in the GDP-bound form and must then exchange GDP for GTP. The 70S ribosome termination complex (70S-TC) accelerates GDP exchange in RF3, suggesting that the 70S-TC can function as the guanine nucleotide exchange factor for RF3. Here, we use cryogenic-electron microscopy to elucidate the mechanism of GDP dissociation from RF3 catalyzed by the Escherichia coli 70S-TC. The non-rotated ribosome bound to RF1 remodels RF3 and induces a peptide flip in the phosphate-binding loop, efficiently ejecting GDP. Binding of GTP allows RF3 to dock at the GTPase center, promoting the dissociation of RF1 from the ribosome. The structures recapitulate the functional cycle of RF3 on the ribosome and uncover the mechanism by which the 70S-TC allosterically dismantles the phosphate-binding groove in RF3, a previously overlooked function of the ribosome. Li et al. reveal the mechanism by which the ribosome termination complex catalyzes dissociation of GDP from release factor RF3 in Escherichia coli. The findings explain the guanine nucleotide exchange factor activity of the ribosome.
{"title":"The ribosome termination complex remodels release factor RF3 and ejects GDP","authors":"Li Li, Mariia Yu. Rybak, Jinzhong Lin, Matthieu G. Gagnon","doi":"10.1038/s41594-024-01360-0","DOIUrl":"10.1038/s41594-024-01360-0","url":null,"abstract":"Translation termination involves release factors RF1, RF2 and the GTPase RF3 that recycles RF1 and RF2 from the ribosome. RF3 dissociates from the ribosome in the GDP-bound form and must then exchange GDP for GTP. The 70S ribosome termination complex (70S-TC) accelerates GDP exchange in RF3, suggesting that the 70S-TC can function as the guanine nucleotide exchange factor for RF3. Here, we use cryogenic-electron microscopy to elucidate the mechanism of GDP dissociation from RF3 catalyzed by the Escherichia coli 70S-TC. The non-rotated ribosome bound to RF1 remodels RF3 and induces a peptide flip in the phosphate-binding loop, efficiently ejecting GDP. Binding of GTP allows RF3 to dock at the GTPase center, promoting the dissociation of RF1 from the ribosome. The structures recapitulate the functional cycle of RF3 on the ribosome and uncover the mechanism by which the 70S-TC allosterically dismantles the phosphate-binding groove in RF3, a previously overlooked function of the ribosome. Li et al. reveal the mechanism by which the ribosome termination complex catalyzes dissociation of GDP from release factor RF3 in Escherichia coli. The findings explain the guanine nucleotide exchange factor activity of the ribosome.","PeriodicalId":49141,"journal":{"name":"Nature Structural & Molecular Biology","volume":"31 12","pages":"1909-1920"},"PeriodicalIF":12.5,"publicationDate":"2024-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141727534","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 : 2024-07-18DOI: 10.1038/s41594-024-01361-z
Ilias Skeparnias, Jinwei Zhang
NEAT1 long noncoding RNA orchestrates paraspeckle assembly and impacts tumorigenesis, fertility and immunity. Its maturation requires RNase P cleavage yielding an unstable transfer RNA-like multiple endocrine neoplasia-β tRNA-like transcript (menRNA) due to CCACCA addition. Here we report the crystal structure of human menRNA, which partially mimics tRNAs to drive RNase P and ELAC2 processing. Biophysical analyses uncover an RNA-centric, riboswitch-like mechanism whereby the nascent CCA reshapes the RNA folding landscape and propels a spontaneous conformational isomerization that directs repeat CCA addition, marking the menRNA and defective tRNAs for degradation. This study reveals the mechanisms of NEAT1 lncRNA maturation and menRNA biogenesis and uncovers an RNA-centric, riboswitch-like mechanism where menRNA drives its own conformational isomerization that directs repeat CCA addition and rapid degradation.
NEAT1 长非编码 RNA 可协调副颈组装，影响肿瘤发生、生育和免疫。它的成熟需要 RNase P 的裂解，由于 CCACCA 的添加，会产生不稳定的类似转移 RNA 的多发性内分泌肿瘤-β tRNA 样转录物（menRNA）。我们在此报告了人类 menRNA 的晶体结构，它部分模拟 tRNA 驱动 RNase P 和 ELAC2 处理。生物物理分析发现了一种以 RNA 为中心的类似核糖开关的机制，新生的 CCA 重塑了 RNA 的折叠结构，并推动了自发的构象异构化，从而引导重复的 CCA 加成，将 menRNA 和有缺陷的 tRNA 标记为降解。
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