Pub Date : 2024-06-04DOI: 10.1038/s41594-024-01328-0
W. Dylan Hale, Alejandra Montaño Romero, Cuauhtemoc U. Gonzalez, Vasanthi Jayaraman, Albert Y. Lau, Richard L. Huganir, Edward C. Twomey
Excitatory neurotransmission is principally mediated by α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-subtype ionotropic glutamate receptors (AMPARs). Negative allosteric modulators are therapeutic candidates that inhibit AMPAR activation and can compete with positive modulators to control AMPAR function through unresolved mechanisms. Here we show that allosteric inhibition pushes AMPARs into a distinct state that prevents both activation and positive allosteric modulation. We used cryo-electron microscopy to capture AMPARs bound to glutamate, while a negative allosteric modulator, GYKI-52466, and positive allosteric modulator, cyclothiazide, compete for control of the AMPARs. GYKI-52466 binds in the ion channel collar and inhibits AMPARs by decoupling the ligand-binding domains from the ion channel. The rearrangement of the ligand-binding domains ruptures the cyclothiazide site, preventing positive modulation. Our data provide a framework for understanding allostery of AMPARs and for rational design of therapeutics targeting AMPARs in neurological diseases. Using cryo-electron microscopy, the authors reveal the mechanism by which perampanel-like molecules inhibit AMPA receptors. They show that the inhibitors decouple the ligand-binding domain from the ion channel after neurotransmitter binding and outcompete positive modulators.
{"title":"Allosteric competition and inhibition in AMPA receptors","authors":"W. Dylan Hale, Alejandra Montaño Romero, Cuauhtemoc U. Gonzalez, Vasanthi Jayaraman, Albert Y. Lau, Richard L. Huganir, Edward C. Twomey","doi":"10.1038/s41594-024-01328-0","DOIUrl":"10.1038/s41594-024-01328-0","url":null,"abstract":"Excitatory neurotransmission is principally mediated by α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-subtype ionotropic glutamate receptors (AMPARs). Negative allosteric modulators are therapeutic candidates that inhibit AMPAR activation and can compete with positive modulators to control AMPAR function through unresolved mechanisms. Here we show that allosteric inhibition pushes AMPARs into a distinct state that prevents both activation and positive allosteric modulation. We used cryo-electron microscopy to capture AMPARs bound to glutamate, while a negative allosteric modulator, GYKI-52466, and positive allosteric modulator, cyclothiazide, compete for control of the AMPARs. GYKI-52466 binds in the ion channel collar and inhibits AMPARs by decoupling the ligand-binding domains from the ion channel. The rearrangement of the ligand-binding domains ruptures the cyclothiazide site, preventing positive modulation. Our data provide a framework for understanding allostery of AMPARs and for rational design of therapeutics targeting AMPARs in neurological diseases. Using cryo-electron microscopy, the authors reveal the mechanism by which perampanel-like molecules inhibit AMPA receptors. They show that the inhibitors decouple the ligand-binding domain from the ion channel after neurotransmitter binding and outcompete positive modulators.","PeriodicalId":49141,"journal":{"name":"Nature Structural & Molecular Biology","volume":"31 11","pages":"1669-1679"},"PeriodicalIF":12.5,"publicationDate":"2024-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41594-024-01328-0.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141246303","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 : 2024-06-04DOI: 10.1038/s41594-024-01325-3
Charbel Alfeghaly, Gaël Castel, Emmanuel Cazottes, Madeleine Moscatelli, Eva Moinard, Miguel Casanova, Juliette Boni, Kasturi Mahadik, Jenna Lammers, Thomas Freour, Louis Chauviere, Carla Piqueras, Ruben Boers, Joachim Boers, Joost Gribnau, Laurent David, Jean-François Ouimette, Claire Rougeulle
XIST (X-inactive specific transcript) long noncoding RNA (lncRNA) is responsible for X chromosome inactivation (XCI) in placental mammals, yet it accumulates on both X chromosomes in human female preimplantation embryos without triggering X chromosome silencing. The XACT (X-active coating transcript) lncRNA coaccumulates with XIST on active X chromosomes and may antagonize XIST function. Here, we used human embryonic stem cells in a naive state of pluripotency to assess the function of XIST and XACT in shaping the X chromosome chromatin and transcriptional landscapes during preimplantation development. We show that XIST triggers the deposition of polycomb-mediated repressive histone modifications and dampens the transcription of most X-linked genes in a SPEN-dependent manner, while XACT deficiency does not significantly affect XIST activity or X-linked gene expression. Our study demonstrates that XIST is functional before XCI, confirms the existence of a transient process of X chromosome dosage compensation and reveals that XCI and dampening rely on the same set of factors. Using naive human embryonic stem cells as a model for early embryogenesis, the authors report that the XIST (X-inactive specific transcript) long noncoding RNA recruits repressive histone marks and attenuates X chromosome expression before the establishment of X chromosome inactivation.
XIST（X-inactive specific transcript）长非编码 RNA（lncRNA）在胎盘哺乳动物中负责 X 染色体失活（XCI），但它会在人类女性植入前胚胎的两条 X 染色体上积累，而不会引发 X 染色体沉默。XACT（X-活性包被转录本）lncRNA与XIST共同聚集在活性X染色体上，可能会拮抗XIST的功能。在这里，我们利用处于幼稚多能状态的人类胚胎干细胞，评估了XIST和XACT在植入前发育过程中塑造X染色体染色质和转录景观的功能。我们的研究表明，XIST 会触发多聚酶介导的抑制性组蛋白修饰沉积，并以一种依赖 SPEN 的方式抑制大多数 X 连锁基因的转录，而 XACT 的缺乏并不会显著影响 XIST 的活性或 X 连锁基因的表达。我们的研究表明，XIST 在 XCI 之前就已发挥作用，证实了 X 染色体剂量补偿过程的存在，并揭示了 XCI 和抑制作用依赖于同一组因子。
{"title":"XIST dampens X chromosome activity in a SPEN-dependent manner during early human development","authors":"Charbel Alfeghaly, Gaël Castel, Emmanuel Cazottes, Madeleine Moscatelli, Eva Moinard, Miguel Casanova, Juliette Boni, Kasturi Mahadik, Jenna Lammers, Thomas Freour, Louis Chauviere, Carla Piqueras, Ruben Boers, Joachim Boers, Joost Gribnau, Laurent David, Jean-François Ouimette, Claire Rougeulle","doi":"10.1038/s41594-024-01325-3","DOIUrl":"10.1038/s41594-024-01325-3","url":null,"abstract":"XIST (X-inactive specific transcript) long noncoding RNA (lncRNA) is responsible for X chromosome inactivation (XCI) in placental mammals, yet it accumulates on both X chromosomes in human female preimplantation embryos without triggering X chromosome silencing. The XACT (X-active coating transcript) lncRNA coaccumulates with XIST on active X chromosomes and may antagonize XIST function. Here, we used human embryonic stem cells in a naive state of pluripotency to assess the function of XIST and XACT in shaping the X chromosome chromatin and transcriptional landscapes during preimplantation development. We show that XIST triggers the deposition of polycomb-mediated repressive histone modifications and dampens the transcription of most X-linked genes in a SPEN-dependent manner, while XACT deficiency does not significantly affect XIST activity or X-linked gene expression. Our study demonstrates that XIST is functional before XCI, confirms the existence of a transient process of X chromosome dosage compensation and reveals that XCI and dampening rely on the same set of factors. Using naive human embryonic stem cells as a model for early embryogenesis, the authors report that the XIST (X-inactive specific transcript) long noncoding RNA recruits repressive histone marks and attenuates X chromosome expression before the establishment of X chromosome inactivation.","PeriodicalId":49141,"journal":{"name":"Nature Structural & Molecular Biology","volume":"31 10","pages":"1589-1600"},"PeriodicalIF":12.5,"publicationDate":"2024-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41594-024-01325-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141246284","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 : 2024-06-04DOI: 10.1038/s41594-024-01300-y
Jagan Mohan, Satish B. Moparthi, Christine Girard-Blanc, Daniele Campisi, Stéphane Blanchard, Charlotte Nugues, Sowmya Rama, Audrey Salles, Esthel Pénard, Stéphane Vassilopoulos, Thomas Wollert
The hallmark of non-selective autophagy is the formation of cup-shaped phagophores that capture bulk cytoplasm. The process is accompanied by the conjugation of LC3B to phagophores by an E3 ligase complex comprising ATG12–ATG5 and ATG16L1. Here we combined two complementary reconstitution approaches to reveal the function of LC3B and its ligase complex during phagophore expansion. We found that LC3B forms together with ATG12–ATG5–ATG16L1 a membrane coat that remodels flat membranes into cups that closely resemble phagophores. Mechanistically, we revealed that cup formation strictly depends on a close collaboration between LC3B and ATG16L1. Moreover, only LC3B, but no other member of the ATG8 protein family, promotes cup formation. ATG16L1 truncates that lacked the C-terminal membrane binding domain catalyzed LC3B lipidation but failed to assemble coats, did not promote cup formation and inhibited the biogenesis of non-selective autophagosomes. Our results thus demonstrate that ATG16L1 and LC3B induce and stabilize the characteristic cup-like shape of phagophores. Autophagy degrades cellular waste by engulfing it in phagophore membranes and delivering it to lysosomes for degradation. Here Mohan and colleagues identified a type of membrane coat that assembles on phagophores to guide their expansion.
{"title":"ATG16L1 induces the formation of phagophore-like membrane cups","authors":"Jagan Mohan, Satish B. Moparthi, Christine Girard-Blanc, Daniele Campisi, Stéphane Blanchard, Charlotte Nugues, Sowmya Rama, Audrey Salles, Esthel Pénard, Stéphane Vassilopoulos, Thomas Wollert","doi":"10.1038/s41594-024-01300-y","DOIUrl":"10.1038/s41594-024-01300-y","url":null,"abstract":"The hallmark of non-selective autophagy is the formation of cup-shaped phagophores that capture bulk cytoplasm. The process is accompanied by the conjugation of LC3B to phagophores by an E3 ligase complex comprising ATG12–ATG5 and ATG16L1. Here we combined two complementary reconstitution approaches to reveal the function of LC3B and its ligase complex during phagophore expansion. We found that LC3B forms together with ATG12–ATG5–ATG16L1 a membrane coat that remodels flat membranes into cups that closely resemble phagophores. Mechanistically, we revealed that cup formation strictly depends on a close collaboration between LC3B and ATG16L1. Moreover, only LC3B, but no other member of the ATG8 protein family, promotes cup formation. ATG16L1 truncates that lacked the C-terminal membrane binding domain catalyzed LC3B lipidation but failed to assemble coats, did not promote cup formation and inhibited the biogenesis of non-selective autophagosomes. Our results thus demonstrate that ATG16L1 and LC3B induce and stabilize the characteristic cup-like shape of phagophores. Autophagy degrades cellular waste by engulfing it in phagophore membranes and delivering it to lysosomes for degradation. Here Mohan and colleagues identified a type of membrane coat that assembles on phagophores to guide their expansion.","PeriodicalId":49141,"journal":{"name":"Nature Structural & Molecular Biology","volume":"31 9","pages":"1448-1459"},"PeriodicalIF":12.5,"publicationDate":"2024-06-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141246273","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 : 2024-05-31DOI: 10.1038/s41594-024-01333-3
Cryo-electron microscopy (cryo-EM) imaging of DNA replication origin activation explains the role of Mcm10, a minichromosome maintenance (MCM) protein homolog, during initiation. Mcm10 acts as a wedge to split the two MCM hexamers of the activated replicative helicase. Diverging replication forks are then established, with changes in the MCM hexamers that promote the topological separation of two DNA strands.
DNA复制源激活的低温电子显微镜（cryo-EM）成像解释了微型染色体维护（MCM）蛋白同源物Mcm10在启动过程中的作用。Mcm10 充当楔子，将激活的复制螺旋酶的两个 MCM 六聚体分开。然后，随着 MCM 六聚体的变化，促进两条 DNA 链拓扑分离的分歧复制叉就建立起来了。
{"title":"How Mcm10 converts the pre-replication complex into two diverging DNA forks","authors":"","doi":"10.1038/s41594-024-01333-3","DOIUrl":"10.1038/s41594-024-01333-3","url":null,"abstract":"Cryo-electron microscopy (cryo-EM) imaging of DNA replication origin activation explains the role of Mcm10, a minichromosome maintenance (MCM) protein homolog, during initiation. Mcm10 acts as a wedge to split the two MCM hexamers of the activated replicative helicase. Diverging replication forks are then established, with changes in the MCM hexamers that promote the topological separation of two DNA strands.","PeriodicalId":49141,"journal":{"name":"Nature Structural & Molecular Biology","volume":"31 8","pages":"1150-1151"},"PeriodicalIF":12.5,"publicationDate":"2024-05-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141182376","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 : 2024-05-30DOI: 10.1038/s41594-024-01324-4
Eva Nogales
Macromolecules are involved in myriads of interactions that regulate their cellular function. While years of structural biology progress was built by reducing this complexity, a molecular understanding of biological processes requires the characterization of ever larger and more dynamic molecular assemblies. Cryo-electron microscopy is rising to this challenge.
{"title":"Building up complexity in structural biology studies","authors":"Eva Nogales","doi":"10.1038/s41594-024-01324-4","DOIUrl":"10.1038/s41594-024-01324-4","url":null,"abstract":"Macromolecules are involved in myriads of interactions that regulate their cellular function. While years of structural biology progress was built by reducing this complexity, a molecular understanding of biological processes requires the characterization of ever larger and more dynamic molecular assemblies. Cryo-electron microscopy is rising to this challenge.","PeriodicalId":49141,"journal":{"name":"Nature Structural & Molecular Biology","volume":"31 6","pages":"847-848"},"PeriodicalIF":16.8,"publicationDate":"2024-05-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141177504","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 : 2024-05-29DOI: 10.1038/s41594-024-01296-5
Ramanujan S. Hegde, Robert J. Keenan
α-Helical integral membrane proteins comprise approximately 25% of the proteome in all organisms. The membrane proteome is highly diverse, varying in the number, topology, spacing and properties of transmembrane domains. This diversity imposes different constraints on the insertion of different regions of a membrane protein into the lipid bilayer. Here, we present a cohesive framework to explain membrane protein biogenesis, in which different parts of a nascent substrate are triaged between Oxa1 and SecY family members for insertion. In this model, Oxa1 family proteins insert transmembrane domains flanked by short translocated segments, whereas the SecY channel is required for insertion of transmembrane domains flanked by long translocated segments. Our unifying model rationalizes evolutionary, genetic, biochemical and structural data across organisms and provides a foundation for future mechanistic studies of membrane protein biogenesis. In this Perspective, the authors propose a framework to explain membrane protein biogenesis, wherein different parts of a nascent substrate are triaged between Oxa1 and SecY family members for insertion.
{"title":"A unifying model for membrane protein biogenesis","authors":"Ramanujan S. Hegde, Robert J. Keenan","doi":"10.1038/s41594-024-01296-5","DOIUrl":"10.1038/s41594-024-01296-5","url":null,"abstract":"α-Helical integral membrane proteins comprise approximately 25% of the proteome in all organisms. The membrane proteome is highly diverse, varying in the number, topology, spacing and properties of transmembrane domains. This diversity imposes different constraints on the insertion of different regions of a membrane protein into the lipid bilayer. Here, we present a cohesive framework to explain membrane protein biogenesis, in which different parts of a nascent substrate are triaged between Oxa1 and SecY family members for insertion. In this model, Oxa1 family proteins insert transmembrane domains flanked by short translocated segments, whereas the SecY channel is required for insertion of transmembrane domains flanked by long translocated segments. Our unifying model rationalizes evolutionary, genetic, biochemical and structural data across organisms and provides a foundation for future mechanistic studies of membrane protein biogenesis. In this Perspective, the authors propose a framework to explain membrane protein biogenesis, wherein different parts of a nascent substrate are triaged between Oxa1 and SecY family members for insertion.","PeriodicalId":49141,"journal":{"name":"Nature Structural & Molecular Biology","volume":"31 7","pages":"1009-1017"},"PeriodicalIF":12.5,"publicationDate":"2024-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141165362","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 : 2024-05-29DOI: 10.1038/s41594-024-01322-6
Junjiao Yang, Chan-I Chung, Jessica Koach, Hongjiang Liu, Ambuja Navalkar, Hao He, Zhimin Ma, Qian Zhao, Xiaoyu Yang, Liang He, Tanja Mittag, Yin Shen, William A. Weiss, Xiaokun Shu
Dysregulation and enhanced expression of MYC transcription factors (TFs) including MYC and MYCN contribute to the majority of human cancers. For example, MYCN is amplified up to several hundredfold in high-risk neuroblastoma. The resulting overexpression of N-myc aberrantly activates genes that are not activated at low N-myc levels and drives cell proliferation. Whether increasing N-myc levels simply mediates binding to lower-affinity binding sites in the genome or fundamentally changes the activation process remains unclear. One such activation mechanism that could become important above threshold levels of N-myc is the formation of aberrant transcriptional condensates through phase separation. Phase separation has recently been linked to transcriptional regulation, but the extent to which it contributes to gene activation remains an open question. Here we characterized the phase behavior of N-myc and showed that it can form dynamic condensates that have transcriptional hallmarks. We tested the role of phase separation in N-myc-regulated transcription by using a chemogenetic tool that allowed us to compare non-phase-separated and phase-separated conditions at equivalent N-myc levels, both of which showed a strong impact on gene expression compared to no N-myc expression. Interestingly, we discovered that only a small percentage (<3%) of N-myc-regulated genes is further modulated by phase separation but that these events include the activation of key oncogenes and the repression of tumor suppressors. Indeed, phase separation increases cell proliferation, corroborating the biological effects of the transcriptional changes. However, our results also show that >97% of N-myc-regulated genes are not affected by N-myc phase separation, demonstrating that soluble complexes of TFs with the transcriptional machinery are sufficient to activate transcription. Oncoprotein transcription factor MYC undergoes phase separation, forming transcriptionally active condensates. The chemogenetic tool SPARK-ON reveals that MYC phase separation selectively modulates the transcriptome and promotes cell proliferation.
{"title":"MYC phase separation selectively modulates the transcriptome","authors":"Junjiao Yang, Chan-I Chung, Jessica Koach, Hongjiang Liu, Ambuja Navalkar, Hao He, Zhimin Ma, Qian Zhao, Xiaoyu Yang, Liang He, Tanja Mittag, Yin Shen, William A. Weiss, Xiaokun Shu","doi":"10.1038/s41594-024-01322-6","DOIUrl":"10.1038/s41594-024-01322-6","url":null,"abstract":"Dysregulation and enhanced expression of MYC transcription factors (TFs) including MYC and MYCN contribute to the majority of human cancers. For example, MYCN is amplified up to several hundredfold in high-risk neuroblastoma. The resulting overexpression of N-myc aberrantly activates genes that are not activated at low N-myc levels and drives cell proliferation. Whether increasing N-myc levels simply mediates binding to lower-affinity binding sites in the genome or fundamentally changes the activation process remains unclear. One such activation mechanism that could become important above threshold levels of N-myc is the formation of aberrant transcriptional condensates through phase separation. Phase separation has recently been linked to transcriptional regulation, but the extent to which it contributes to gene activation remains an open question. Here we characterized the phase behavior of N-myc and showed that it can form dynamic condensates that have transcriptional hallmarks. We tested the role of phase separation in N-myc-regulated transcription by using a chemogenetic tool that allowed us to compare non-phase-separated and phase-separated conditions at equivalent N-myc levels, both of which showed a strong impact on gene expression compared to no N-myc expression. Interestingly, we discovered that only a small percentage (<3%) of N-myc-regulated genes is further modulated by phase separation but that these events include the activation of key oncogenes and the repression of tumor suppressors. Indeed, phase separation increases cell proliferation, corroborating the biological effects of the transcriptional changes. However, our results also show that >97% of N-myc-regulated genes are not affected by N-myc phase separation, demonstrating that soluble complexes of TFs with the transcriptional machinery are sufficient to activate transcription. Oncoprotein transcription factor MYC undergoes phase separation, forming transcriptionally active condensates. The chemogenetic tool SPARK-ON reveals that MYC phase separation selectively modulates the transcriptome and promotes cell proliferation.","PeriodicalId":49141,"journal":{"name":"Nature Structural & Molecular Biology","volume":"31 10","pages":"1567-1579"},"PeriodicalIF":12.5,"publicationDate":"2024-05-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41594-024-01322-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141165114","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 : 2024-05-28DOI: 10.1038/s41594-024-01323-5
Jochen Kuper, Tamsanqa Hove, Sarah Maidl, Hermann Neitz, Florian Sauer, Maximilian Kempf, Till Schroeder, Elke Greiter, Claudia Höbartner, Caroline Kisker
The superfamily 2 helicase XPD is a central component of the general transcription factor II H (TFIIH), which is essential for transcription and nucleotide excision DNA repair (NER). Within these two processes, the helicase function of XPD is vital for NER but not for transcription initiation, where XPD acts only as a scaffold for other factors. Using cryo-EM, we deciphered one of the most enigmatic steps in XPD helicase action: the active separation of double-stranded DNA (dsDNA) and its stalling upon approaching a DNA interstrand cross-link, a highly toxic form of DNA damage. The structure shows how dsDNA is separated and reveals a highly unusual involvement of the Arch domain in active dsDNA separation. Combined with mutagenesis and biochemical analyses, we identified distinct functional regions important for helicase activity. Surprisingly, those areas also affect core TFIIH translocase activity, revealing a yet unencountered function of XPD within the TFIIH scaffold. In summary, our data provide a universal basis for NER bubble formation, XPD damage verification and XPG incision. Here, using cryo-EM and biochemistry, the authors delineate how the XPD helicase unorthodoxly uses its Arch domain to separate double-stranded DNA upon approaching a DNA lesion, promoting our understanding of NER bubble formation and damage verification.
超家族 2 螺旋酶 XPD 是一般转录因子 II H（TFIIH）的核心成分，它对转录和核苷酸切割 DNA 修复（NER）至关重要。在这两个过程中，XPD 的螺旋酶功能对 NER 至关重要，但对转录起始并不重要，在转录起始过程中，XPD 只充当其他因子的支架。我们利用低温电子显微镜破译了 XPD 螺旋酶作用中最神秘的步骤之一：主动分离双链 DNA（dsDNA），并在接近 DNA 链间交联（一种剧毒的 DNA 损伤形式）时停滞。该结构显示了dsDNA是如何分离的，并揭示了Arch结构域在主动分离dsDNA过程中极不寻常的参与。结合诱变和生化分析，我们确定了对螺旋酶活性非常重要的不同功能区。令人惊讶的是，这些区域也影响了 TFIIH 核心转位酶的活性，揭示了 XPD 在 TFIIH 支架中尚未遇到的功能。总之，我们的数据为 NER 气泡形成、XPD 损伤验证和 XPG 切割提供了一个普遍基础。
{"title":"XPD stalled on cross-linked DNA provides insight into damage verification","authors":"Jochen Kuper, Tamsanqa Hove, Sarah Maidl, Hermann Neitz, Florian Sauer, Maximilian Kempf, Till Schroeder, Elke Greiter, Claudia Höbartner, Caroline Kisker","doi":"10.1038/s41594-024-01323-5","DOIUrl":"10.1038/s41594-024-01323-5","url":null,"abstract":"The superfamily 2 helicase XPD is a central component of the general transcription factor II H (TFIIH), which is essential for transcription and nucleotide excision DNA repair (NER). Within these two processes, the helicase function of XPD is vital for NER but not for transcription initiation, where XPD acts only as a scaffold for other factors. Using cryo-EM, we deciphered one of the most enigmatic steps in XPD helicase action: the active separation of double-stranded DNA (dsDNA) and its stalling upon approaching a DNA interstrand cross-link, a highly toxic form of DNA damage. The structure shows how dsDNA is separated and reveals a highly unusual involvement of the Arch domain in active dsDNA separation. Combined with mutagenesis and biochemical analyses, we identified distinct functional regions important for helicase activity. Surprisingly, those areas also affect core TFIIH translocase activity, revealing a yet unencountered function of XPD within the TFIIH scaffold. In summary, our data provide a universal basis for NER bubble formation, XPD damage verification and XPG incision. Here, using cryo-EM and biochemistry, the authors delineate how the XPD helicase unorthodoxly uses its Arch domain to separate double-stranded DNA upon approaching a DNA lesion, promoting our understanding of NER bubble formation and damage verification.","PeriodicalId":49141,"journal":{"name":"Nature Structural & Molecular Biology","volume":"31 10","pages":"1580-1588"},"PeriodicalIF":12.5,"publicationDate":"2024-05-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41594-024-01323-5.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141159521","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 : 2024-05-24DOI: 10.1038/s41594-024-01314-6
Yingxia Hu, Krista A. Delviks-Frankenberry, Chunxiang Wu, Fidel Arizaga, Vinay K. Pathak, Yong Xiong
HIV-1 Vif recruits host cullin-RING-E3 ubiquitin ligase and CBFβ to degrade the cellular APOBEC3 antiviral proteins through diverse interactions. Recent evidence has shown that Vif also degrades the regulatory subunits PPP2R5(A–E) of cellular protein phosphatase 2A to induce G2/M cell cycle arrest. As PPP2R5 proteins bear no functional or structural resemblance to A3s, it is unclear how Vif can recognize different sets of proteins. Here we report the cryogenic-electron microscopy structure of PPP2R5A in complex with HIV-1 Vif–CBFβ–elongin B–elongin C at 3.58 Å resolution. The structure shows PPP2R5A binds across the Vif molecule, with biochemical and cellular studies confirming a distinct Vif–PPP2R5A interface that partially overlaps with those for A3s. Vif also blocks a canonical PPP2R5A substrate-binding site, indicating that it suppresses the phosphatase activities through both degradation-dependent and degradation-independent mechanisms. Our work identifies critical Vif motifs regulating the recognition of diverse A3 and PPP2R5A substrates, whereby disruption of these host–virus protein interactions could serve as potential targets for HIV-1 therapeutics. The authors solve a cryo-EM structure of the regulatory subunit of human protein phosphatase 2A in complex with HIV-1 Vif-containing E3 ligase, leading to improvement of our understanding of host–virus protein interactions.
{"title":"Structural insights into PPP2R5A degradation by HIV-1 Vif","authors":"Yingxia Hu, Krista A. Delviks-Frankenberry, Chunxiang Wu, Fidel Arizaga, Vinay K. Pathak, Yong Xiong","doi":"10.1038/s41594-024-01314-6","DOIUrl":"10.1038/s41594-024-01314-6","url":null,"abstract":"HIV-1 Vif recruits host cullin-RING-E3 ubiquitin ligase and CBFβ to degrade the cellular APOBEC3 antiviral proteins through diverse interactions. Recent evidence has shown that Vif also degrades the regulatory subunits PPP2R5(A–E) of cellular protein phosphatase 2A to induce G2/M cell cycle arrest. As PPP2R5 proteins bear no functional or structural resemblance to A3s, it is unclear how Vif can recognize different sets of proteins. Here we report the cryogenic-electron microscopy structure of PPP2R5A in complex with HIV-1 Vif–CBFβ–elongin B–elongin C at 3.58 Å resolution. The structure shows PPP2R5A binds across the Vif molecule, with biochemical and cellular studies confirming a distinct Vif–PPP2R5A interface that partially overlaps with those for A3s. Vif also blocks a canonical PPP2R5A substrate-binding site, indicating that it suppresses the phosphatase activities through both degradation-dependent and degradation-independent mechanisms. Our work identifies critical Vif motifs regulating the recognition of diverse A3 and PPP2R5A substrates, whereby disruption of these host–virus protein interactions could serve as potential targets for HIV-1 therapeutics. The authors solve a cryo-EM structure of the regulatory subunit of human protein phosphatase 2A in complex with HIV-1 Vif-containing E3 ligase, leading to improvement of our understanding of host–virus protein interactions.","PeriodicalId":49141,"journal":{"name":"Nature Structural & Molecular Biology","volume":"31 10","pages":"1492-1501"},"PeriodicalIF":12.5,"publicationDate":"2024-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141092183","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 : 2024-05-24DOI: 10.1038/s41594-024-01311-9
Meng Zhu, Maciej Meglicki, Adiyant Lamba, Peizhe Wang, Christophe Royer, Karen Turner, Muhammad Abdullah Jauhar, Celine Jones, Tim Child, Kevin Coward, Jie Na, Magdalena Zernicka-Goetz
The mouse and human embryo gradually loses totipotency before diversifying into the inner cell mass (ICM, future organism) and trophectoderm (TE, future placenta). The transcription factors TFAP2C and TEAD4 with activated RHOA accelerate embryo polarization. Here we show that these factors also accelerate the loss of totipotency. TFAP2C and TEAD4 paradoxically promote and inhibit Hippo signaling before lineage diversification: they drive expression of multiple Hippo regulators while also promoting apical domain formation, which inactivates Hippo. Each factor activates TE specifiers in bipotent cells, while TFAP2C also activates specifiers of the ICM fate. Asymmetric segregation of the apical domain reconciles the opposing regulation of Hippo signaling into Hippo OFF and the TE fate, or Hippo ON and the ICM fate. We propose that the bistable switch established by TFAP2C and TEAD4 is exploited to trigger robust lineage diversification in the developing embryo. Here the authors identify the transcription factors TFAP2C and TEAD4 as a bistable switch that reconciles into Hippo ON and OFF states, establishing a composite state at the eight-cell stage and critically regulating lineage diversification.
{"title":"Tead4 and Tfap2c generate bipotency and a bistable switch in totipotent embryos to promote robust lineage diversification","authors":"Meng Zhu, Maciej Meglicki, Adiyant Lamba, Peizhe Wang, Christophe Royer, Karen Turner, Muhammad Abdullah Jauhar, Celine Jones, Tim Child, Kevin Coward, Jie Na, Magdalena Zernicka-Goetz","doi":"10.1038/s41594-024-01311-9","DOIUrl":"10.1038/s41594-024-01311-9","url":null,"abstract":"The mouse and human embryo gradually loses totipotency before diversifying into the inner cell mass (ICM, future organism) and trophectoderm (TE, future placenta). The transcription factors TFAP2C and TEAD4 with activated RHOA accelerate embryo polarization. Here we show that these factors also accelerate the loss of totipotency. TFAP2C and TEAD4 paradoxically promote and inhibit Hippo signaling before lineage diversification: they drive expression of multiple Hippo regulators while also promoting apical domain formation, which inactivates Hippo. Each factor activates TE specifiers in bipotent cells, while TFAP2C also activates specifiers of the ICM fate. Asymmetric segregation of the apical domain reconciles the opposing regulation of Hippo signaling into Hippo OFF and the TE fate, or Hippo ON and the ICM fate. We propose that the bistable switch established by TFAP2C and TEAD4 is exploited to trigger robust lineage diversification in the developing embryo. Here the authors identify the transcription factors TFAP2C and TEAD4 as a bistable switch that reconciles into Hippo ON and OFF states, establishing a composite state at the eight-cell stage and critically regulating lineage diversification.","PeriodicalId":49141,"journal":{"name":"Nature Structural & Molecular Biology","volume":"31 6","pages":"964-976"},"PeriodicalIF":16.8,"publicationDate":"2024-05-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s41594-024-01311-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141092133","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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