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Yang Y, Murrali MG, Wang Y, Galvan S, Ajjampore N, Feigon J. HEXIM1 homodimer binds two sites on 7SK RNA to release autoinhibition for P-TEFb inactivation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.10.10.617642. [PMID: 39416148 PMCID: PMC11482958 DOI: 10.1101/2024.10.10.617642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2024]
Abstract
Hexim proteins are RNA-dependent regulators whose main target is 7SK long non-coding RNA, a major regulator of eukaryotic mRNA transcription. 7SK RNPs control available intracellular concentrations of the kinase P-TEFb (Cdk9-CyclinT1/2) by sequestering it in an inactive form. Active P-TEFb phosphorylates NELF, DSIF, and the RNA polymerase II CTD to transition it from promoter-proximal pausing to productive elongation. P-TEFb associates with 7SK RNP via Hexim, which directly binds 7SK RNA. However, free Hexim is in an autoinhibited state that cannot inactivate P-TEFb, and how Hexim autoinhibition is released by 7SK remains unknown. Here, we show that one Hexim1 homodimer binds two sites on linear 7SK RNA in a manner that exposes the Cdk9 binding sites, which are otherwise masked within the autoinhibited dimer. These results provide mechanistic insights into Hexim-RNA specificity and explain how P-TEFb can be effectively regulated to respond to changing levels of transcriptional signaling.
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2
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Qu Y, Gao N, Zhang S, Gao L, He B, Wang C, Gong C, Shi Q, Li Z, Yang S, Xiao Y. Role of N6-methyladenosine RNA modification in cancer. MedComm (Beijing) 2024; 5:e715. [PMID: 39252821 PMCID: PMC11381670 DOI: 10.1002/mco2.715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2024] [Revised: 08/13/2024] [Accepted: 08/13/2024] [Indexed: 09/11/2024] Open
Abstract
N6-methyladenosine (m6A) is the most abundant modification of RNA in eukaryotic cells. Previous studies have shown that m6A is pivotal in diverse diseases especially cancer. m6A corelates with the initiation, progression, resistance, invasion, and metastasis of cancer. However, despite these insights, a comprehensive understanding of its specific roles and mechanisms within the complex landscape of cancer is still elusive. This review begins by outlining the key regulatory proteins of m6A modification and their posttranslational modifications (PTMs), as well as the role in chromatin accessibility and transcriptional activity within cancer cells. Additionally, it highlights that m6A modifications impact cancer progression by modulating programmed cell death mechanisms and affecting the tumor microenvironment through various cancer-associated immune cells. Furthermore, the review discusses how microorganisms can induce enduring epigenetic changes and oncogenic effect in microorganism-associated cancers by altering m6A modifications. Last, it delves into the role of m6A modification in cancer immunotherapy, encompassing RNA therapy, immune checkpoint blockade, cytokine therapy, adoptive cell transfer therapy, and direct targeting of m6A regulators. Overall, this review clarifies the multifaceted role of m6A modification in cancer and explores targeted therapies aimed at manipulating m6A modification, aiming to advance cancer research and improve patient outcomes.
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Affiliation(s)
- Yi Qu
- Department of Gastroenterology Xinqiao Hospital Army Medical University Chongqing China
| | - Nannan Gao
- Department of Gastroenterology Xinqiao Hospital Army Medical University Chongqing China
| | - Shengwei Zhang
- Department of Gastroenterology Xinqiao Hospital Army Medical University Chongqing China
| | - Limin Gao
- Department of Gastroenterology Xinqiao Hospital Army Medical University Chongqing China
| | - Bing He
- Department of Gastroenterology Xinqiao Hospital Army Medical University Chongqing China
| | - Chao Wang
- Department of Gastroenterology Xinqiao Hospital Army Medical University Chongqing China
| | - Chunli Gong
- Department of Gastroenterology Xinqiao Hospital Army Medical University Chongqing China
| | - Qiuyue Shi
- Department of Gastroenterology the First Affiliated Hospital of Guangxi Medical University Nanning Guangxi China
| | - Zhibin Li
- Department of Gastroenterology Xinqiao Hospital Army Medical University Chongqing China
| | - Shiming Yang
- Department of Gastroenterology Xinqiao Hospital Army Medical University Chongqing China
| | - Yufeng Xiao
- Department of Gastroenterology Xinqiao Hospital Army Medical University Chongqing China
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3
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Chen XH, Guo KX, Li J, Xu SH, Zhu H, Yan GR. Regulations of m 6A and other RNA modifications and their roles in cancer. Front Med 2024; 18:622-648. [PMID: 38907157 DOI: 10.1007/s11684-024-1064-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Accepted: 01/17/2024] [Indexed: 06/23/2024]
Abstract
RNA modification is an essential component of the epitranscriptome, regulating RNA metabolism and cellular functions. Several types of RNA modifications have been identified to date; they include N6-methyladenosine (m6A), N1-methyladenosine (m1A), 5-methylcytosine (m5C), N7-methylguanosine (m7G), N6,2'-O-dimethyladenosine (m6Am), N4-acetylcytidine (ac4C), etc. RNA modifications, mediated by regulators including writers, erasers, and readers, are associated with carcinogenesis, tumor microenvironment, metabolic reprogramming, immunosuppression, immunotherapy, chemotherapy, etc. A novel perspective indicates that regulatory subunits and post-translational modifications (PTMs) are involved in the regulation of writer, eraser, and reader functions in mediating RNA modifications, tumorigenesis, and anticancer therapy. In this review, we summarize the advances made in the knowledge of different RNA modifications (especially m6A) and focus on RNA modification regulators with functions modulated by a series of factors in cancer, including regulatory subunits (proteins, noncoding RNA or peptides encoded by long noncoding RNA) and PTMs (acetylation, SUMOylation, lactylation, phosphorylation, etc.). We also delineate the relationship between RNA modification regulator functions and carcinogenesis or cancer progression. Additionally, inhibitors that target RNA modification regulators for anticancer therapy and their synergistic effect combined with immunotherapy or chemotherapy are discussed.
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Affiliation(s)
- Xin-Hui Chen
- Biomedicine Research Center, Guangdong Provincial Key Laboratory of Major Obstetric Disease, Guangdong Provincial Clinical Research Center for Obstetrics and Gynecology, State Key Laboratory of Respiratory Disease, the Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510150, China
| | - Kun-Xiong Guo
- Biomedicine Research Center, Guangdong Provincial Key Laboratory of Major Obstetric Disease, Guangdong Provincial Clinical Research Center for Obstetrics and Gynecology, State Key Laboratory of Respiratory Disease, the Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510150, China
| | - Jing Li
- Biomedicine Research Center, Guangdong Provincial Key Laboratory of Major Obstetric Disease, Guangdong Provincial Clinical Research Center for Obstetrics and Gynecology, State Key Laboratory of Respiratory Disease, the Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510150, China
| | - Shu-Hui Xu
- Biomedicine Research Center, Guangdong Provincial Key Laboratory of Major Obstetric Disease, Guangdong Provincial Clinical Research Center for Obstetrics and Gynecology, State Key Laboratory of Respiratory Disease, the Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510150, China
| | - Huifang Zhu
- Biomedicine Research Center, Guangdong Provincial Key Laboratory of Major Obstetric Disease, Guangdong Provincial Clinical Research Center for Obstetrics and Gynecology, State Key Laboratory of Respiratory Disease, the Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510150, China
| | - Guang-Rong Yan
- Biomedicine Research Center, Guangdong Provincial Key Laboratory of Major Obstetric Disease, Guangdong Provincial Clinical Research Center for Obstetrics and Gynecology, State Key Laboratory of Respiratory Disease, the Third Affiliated Hospital of Guangzhou Medical University, Guangzhou, 510150, China.
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4
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Allen MC, Karplus PA, Mehl RA, Cooley RB. Genetic Encoding of Phosphorylated Amino Acids into Proteins. Chem Rev 2024; 124:6592-6642. [PMID: 38691379 DOI: 10.1021/acs.chemrev.4c00110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2024]
Abstract
Reversible phosphorylation is a fundamental mechanism for controlling protein function. Despite the critical roles phosphorylated proteins play in physiology and disease, our ability to study individual phospho-proteoforms has been hindered by a lack of versatile methods to efficiently generate homogeneous proteins with site-specific phosphoamino acids or with functional mimics that are resistant to phosphatases. Genetic code expansion (GCE) is emerging as a transformative approach to tackle this challenge, allowing direct incorporation of phosphoamino acids into proteins during translation in response to amber stop codons. This genetic programming of phospho-protein synthesis eliminates the reliance on kinase-based or chemical semisynthesis approaches, making it broadly applicable to diverse phospho-proteoforms. In this comprehensive review, we provide a brief introduction to GCE and trace the development of existing GCE technologies for installing phosphoserine, phosphothreonine, phosphotyrosine, and their mimics, discussing both their advantages as well as their limitations. While some of the technologies are still early in their development, others are already robust enough to greatly expand the range of biologically relevant questions that can be addressed. We highlight new discoveries enabled by these GCE approaches, provide practical considerations for the application of technologies by non-GCE experts, and also identify avenues ripe for further development.
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Affiliation(s)
- Michael C Allen
- Department of Biochemistry and Biophysics, Oregon State University, GCE4All Research Center, 2011 Agricultural and Life Sciences, Corvallis, Oregon 97331 United States
| | - P Andrew Karplus
- Department of Biochemistry and Biophysics, Oregon State University, GCE4All Research Center, 2011 Agricultural and Life Sciences, Corvallis, Oregon 97331 United States
| | - Ryan A Mehl
- Department of Biochemistry and Biophysics, Oregon State University, GCE4All Research Center, 2011 Agricultural and Life Sciences, Corvallis, Oregon 97331 United States
| | - Richard B Cooley
- Department of Biochemistry and Biophysics, Oregon State University, GCE4All Research Center, 2011 Agricultural and Life Sciences, Corvallis, Oregon 97331 United States
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5
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Mbonye U, Karn J. The cell biology of HIV-1 latency and rebound. Retrovirology 2024; 21:6. [PMID: 38580979 PMCID: PMC10996279 DOI: 10.1186/s12977-024-00639-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/07/2024] Open
Abstract
Transcriptionally latent forms of replication-competent proviruses, present primarily in a small subset of memory CD4+ T cells, pose the primary barrier to a cure for HIV-1 infection because they are the source of the viral rebound that almost inevitably follows the interruption of antiretroviral therapy. Over the last 30 years, many of the factors essential for initiating HIV-1 transcription have been identified in studies performed using transformed cell lines, such as the Jurkat T-cell model. However, as highlighted in this review, several poorly understood mechanisms still need to be elucidated, including the molecular basis for promoter-proximal pausing of the transcribing complex and the detailed mechanism of the delivery of P-TEFb from 7SK snRNP. Furthermore, the central paradox of HIV-1 transcription remains unsolved: how are the initial rounds of transcription achieved in the absence of Tat? A critical limitation of the transformed cell models is that they do not recapitulate the transitions between active effector cells and quiescent memory T cells. Therefore, investigation of the molecular mechanisms of HIV-1 latency reversal and LRA efficacy in a proper physiological context requires the utilization of primary cell models. Recent mechanistic studies of HIV-1 transcription using latently infected cells recovered from donors and ex vivo cellular models of viral latency have demonstrated that the primary blocks to HIV-1 transcription in memory CD4+ T cells are restrictive epigenetic features at the proviral promoter, the cytoplasmic sequestration of key transcription initiation factors such as NFAT and NF-κB, and the vanishingly low expression of the cellular transcription elongation factor P-TEFb. One of the foremost schemes to eliminate the residual reservoir is to deliberately reactivate latent HIV-1 proviruses to enable clearance of persisting latently infected cells-the "Shock and Kill" strategy. For "Shock and Kill" to become efficient, effective, non-toxic latency-reversing agents (LRAs) must be discovered. Since multiple restrictions limit viral reactivation in primary cells, understanding the T-cell signaling mechanisms that are essential for stimulating P-TEFb biogenesis, initiation factor activation, and reversing the proviral epigenetic restrictions have become a prerequisite for the development of more effective LRAs.
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Affiliation(s)
- Uri Mbonye
- Department of Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA.
| | - Jonathan Karn
- Department of Molecular Biology and Microbiology, Case Western Reserve University School of Medicine, Cleveland, OH, 44106, USA.
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6
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Amir N, Taube R. Role of long noncoding RNA in regulating HIV infection-a comprehensive review. mBio 2024; 15:e0192523. [PMID: 38179937 PMCID: PMC10865847 DOI: 10.1128/mbio.01925-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2024] Open
Abstract
A complete cure against human immunodeficiency virus (HIV) infection remains out of reach, as the virus persists in stable cell reservoirs that are resistant to antiretroviral therapy. The key to eliminating these reservoirs lies in deciphering the processes that govern viral gene expression and latency. However, while we comprehensively understand how host proteins influence HIV gene expression and viral latency, the emerging role of long noncoding RNAs (lncRNAs) in the context of T cell activation, HIV gene expression, and viral latency remain unexplored. This review dives into the evolving significance of lncRNAs and their impact on HIV gene expression and viral latency. We provide an overview of the current knowledge regarding how lncRNAs regulate HIV gene expression, categorizing them as either activators or inhibitors of viral gene expression and infectivity. Furthermore, we offer insights into the potential therapeutic applications of lncRNAs in combatting HIV. A deeper understanding of how lncRNAs modulate HIV gene transcription holds promise for developing novel RNA-based therapies to complement existing treatment strategies to eradicate HIV reservoirs.
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Affiliation(s)
- Noa Amir
- The Shraga Segal Department of Microbiology Immunology and Genetics, Faculty of Health Sciences, Ben-Gurion University of the Negev, Negev, Israel
| | - Ran Taube
- The Shraga Segal Department of Microbiology Immunology and Genetics, Faculty of Health Sciences, Ben-Gurion University of the Negev, Negev, Israel
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7
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Palumbo RJ, Yang Y, Feigon J, Hanes SD. Catalytic activity of the Bin3/MePCE methyltransferase domain is dispensable for 7SK snRNP function in Drosophila melanogaster. Genetics 2024; 226:iyad203. [PMID: 37982586 PMCID: PMC10763541 DOI: 10.1093/genetics/iyad203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 10/27/2023] [Accepted: 11/13/2023] [Indexed: 11/21/2023] Open
Abstract
Methylphosphate Capping Enzyme (MePCE) monomethylates the gamma phosphate at the 5' end of the 7SK noncoding RNA, a modification thought to protect 7SK from degradation. 7SK serves as a scaffold for assembly of a snRNP complex that inhibits transcription by sequestering the positive elongation factor P-TEFb. While much is known about the biochemical activity of MePCE in vitro, little is known about its functions in vivo, or what roles-if any-there are for regions outside the conserved methyltransferase domain. Here, we investigated the role of Bin3, the Drosophila ortholog of MePCE, and its conserved functional domains in Drosophila development. We found that bin3 mutant females had strongly reduced rates of egg-laying, which was rescued by genetic reduction of P-TEFb activity, suggesting that Bin3 promotes fecundity by repressing P-TEFb. bin3 mutants also exhibited neuromuscular defects, analogous to a patient with MePCE haploinsufficiency. These defects were also rescued by genetic reduction of P-TEFb activity, suggesting that Bin3 and MePCE have conserved roles in promoting neuromuscular function by repressing P-TEFb. Unexpectedly, we found that a Bin3 catalytic mutant (Bin3Y795A) could still bind and stabilize 7SK and rescue all bin3 mutant phenotypes, indicating that Bin3 catalytic activity is dispensable for 7SK stability and snRNP function in vivo. Finally, we identified a metazoan-specific motif (MSM) outside of the methyltransferase domain and generated mutant flies lacking this motif (Bin3ΔMSM). Bin3ΔMSM mutant flies exhibited some-but not all-bin3 mutant phenotypes, suggesting that the MSM is required for a 7SK-independent, tissue-specific function of Bin3.
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Affiliation(s)
- Ryan J Palumbo
- Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University, Syracuse, NY 13210, USA
| | - Yuan Yang
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
| | - Juli Feigon
- Department of Chemistry and Biochemistry, University of California, Los Angeles, CA 90095, USA
| | - Steven D Hanes
- Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University, Syracuse, NY 13210, USA
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8
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Höfler S, Duss O. Interconnections between m 6A RNA modification, RNA structure, and protein-RNA complex assembly. Life Sci Alliance 2024; 7:e202302240. [PMID: 37935465 PMCID: PMC10629537 DOI: 10.26508/lsa.202302240] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Revised: 10/31/2023] [Accepted: 10/31/2023] [Indexed: 11/09/2023] Open
Abstract
Protein-RNA complexes exist in many forms within the cell, from stable machines such as the ribosome to transient assemblies like the spliceosome. All protein-RNA assemblies rely on spatially and temporally coordinated interactions between specific proteins and RNAs to achieve a functional form. RNA folding and structure are often critical for successful protein binding and protein-RNA complex formation. RNA modifications change the chemical nature of a given RNA and often alter its folding kinetics. Both these alterations can affect how and if proteins or other RNAs can interact with the modified RNA and assemble into complexes. N6-methyladenosine (m6A) is the most common base modification on mRNAs and regulatory noncoding RNAs and has been shown to impact RNA structure and directly modulate protein-RNA interactions. In this review, focusing on the mechanisms and available quantitative information, we discuss first how the METTL3/14 m6A writer complex is specifically targeted to RNA assisted by protein-RNA and other interactions to enable site-specific and co-transcriptional RNA modification and, once introduced, how the m6A modification affects RNA folding and protein-RNA interactions.
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Affiliation(s)
- Simone Höfler
- https://ror.org/03mstc592 Structural and Computational Biology Unit, EMBL Heidelberg, Heidelberg, Germany
| | - Olivier Duss
- https://ror.org/03mstc592 Structural and Computational Biology Unit, EMBL Heidelberg, Heidelberg, Germany
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9
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Bhattarai PY, Kim G, Bhandari D, Shrestha P, Choi HS. Regulation of m 6A Methylome in Cancer: Mechanisms, Implications, and Therapeutic Strategies. Cells 2023; 13:66. [PMID: 38201270 PMCID: PMC10778393 DOI: 10.3390/cells13010066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2023] [Revised: 12/16/2023] [Accepted: 12/27/2023] [Indexed: 01/12/2024] Open
Abstract
Reversible N6-adenosine methylation of mRNA, referred to as m6A modification, has emerged as an important regulator of post-transcriptional RNA processing. Numerous studies have highlighted its crucial role in the pathogenesis of diverse diseases, particularly cancer. Post-translational modifications of m6A-related proteins play a fundamental role in regulating the m6A methylome, thereby influencing the fate of m6A-methylated RNA. A comprehensive understanding of the mechanisms that regulate m6A-related proteins and the factors contributing to the specificity of m6A deposition has the potential to unveil novel therapeutic strategies for cancer treatment. This review provides an in-depth overview of our current knowledge of post-translational modifications of m6A-related proteins, associated signaling pathways, and the mechanisms that drive the specificity of m6A modifications. Additionally, we explored the role of m6A-dependent mechanisms in the progression of various human cancers. Together, this review summarizes the mechanisms underlying the regulation of the m6A methylome to provide insight into its potential as a novel therapeutic strategy for the treatment of cancer.
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Affiliation(s)
| | | | | | | | - Hong Seok Choi
- College of Pharmacy, Chosun University, Gwangju 61452, Republic of Korea; (P.Y.B.); (G.K.); (D.B.); (P.S.)
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10
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Wang Y, Traugot CM, Bubenik JL, Li T, Sheng P, Hiers NM, Fernandez P, Li L, Bian J, Swanson MS, Xie M. N 6-methyladenosine in 7SK small nuclear RNA underlies RNA polymerase II transcription regulation. Mol Cell 2023; 83:3818-3834.e7. [PMID: 37820733 PMCID: PMC10873123 DOI: 10.1016/j.molcel.2023.09.020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Revised: 08/07/2023] [Accepted: 09/13/2023] [Indexed: 10/13/2023]
Abstract
N6-methyladenosine (m6A) modifications play crucial roles in RNA metabolism. How m6A regulates RNA polymerase II (RNA Pol II) transcription remains unclear. We find that 7SK small nuclear RNA (snRNA), a regulator of RNA Pol II promoter-proximal pausing, is highly m6A-modified in non-small cell lung cancer (NSCLC) cells. In A549 cells, we identified eight m6A sites on 7SK and discovered methyltransferase-like 3 (METTL3) and alkB homolog 5 (ALKBH5) as the responsible writer and eraser. When the m6A-7SK is specifically erased by a dCasRx-ALKBH5 fusion protein, A549 cell growth is attenuated due to reduction of RNA Pol II transcription. Mechanistically, removal of m6A leads to 7SK structural rearrangements that facilitate sequestration of the positive transcription elongation factor b (P-TEFb) complex, which results in reduction of serine 2 phosphorylation (Ser2P) in the RNA Pol II C-terminal domain and accumulation of RNA Pol II in the promoter-proximal region. Taken together, we uncover that m6A modifications of a non-coding RNA regulate RNA Pol II transcription and NSCLC tumorigenesis.
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Affiliation(s)
- Yuzhi Wang
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32610, USA; UF Health Cancer Center, University of Florida, Gainesville, FL 32610, USA
| | - Conner M Traugot
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32610, USA; UF Health Cancer Center, University of Florida, Gainesville, FL 32610, USA
| | - Jodi L Bubenik
- Department of Molecular Genetics & Microbiology, University of Florida, Gainesville, FL 32610, USA; UF Genetics Institute, University of Florida, Gainesville, FL 32610, USA
| | - Tianqi Li
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32610, USA; UF Health Cancer Center, University of Florida, Gainesville, FL 32610, USA
| | - Peike Sheng
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32610, USA; UF Health Cancer Center, University of Florida, Gainesville, FL 32610, USA
| | - Nicholas M Hiers
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32610, USA; UF Health Cancer Center, University of Florida, Gainesville, FL 32610, USA
| | - Paul Fernandez
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32610, USA; UF Health Cancer Center, University of Florida, Gainesville, FL 32610, USA
| | - Lu Li
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32610, USA; UF Health Cancer Center, University of Florida, Gainesville, FL 32610, USA
| | - Jiang Bian
- UF Health Cancer Center, University of Florida, Gainesville, FL 32610, USA; Department of Health Outcomes & Biomedical Informatics, University of Florida, Gainesville, FL 32610, USA
| | - Maurice S Swanson
- Department of Molecular Genetics & Microbiology, University of Florida, Gainesville, FL 32610, USA; UF Genetics Institute, University of Florida, Gainesville, FL 32610, USA
| | - Mingyi Xie
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL 32610, USA; UF Health Cancer Center, University of Florida, Gainesville, FL 32610, USA; UF Genetics Institute, University of Florida, Gainesville, FL 32610, USA.
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11
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Qi S, Gupta YK. A cryptic pocket in METTL3-METTL14 regulates m 6A conversion and sensing. RESEARCH SQUARE 2023:rs.3.rs-3150186. [PMID: 37609305 PMCID: PMC10441475 DOI: 10.21203/rs.3.rs-3150186/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/24/2023]
Abstract
The nuclear METTL3-METTL14 enzyme complex transfers a methyl group from S-adenosyl-L-methionine (SAM) to the N6 amino group of an adenosine (A) base in RNA to convert it to m6A and in ssDNA to 6mA. m6A marks are prevalent in eukaryotic mRNAs and lncRNAs and modulate their stability and fate in a context-dependent manner. The cytoplasmic METTL3 can act as a m6A reader to regulate mRNA translation. However, the precise mechanism that actuates the switch from m6A writer to reader/sensor is unclear. Here, we present a ~2.5Å crystal structure of the methyltransferase core of human METTL3-METTL14 in complex with the reaction product, N6-methyladenosine monophosphate (m6A), representing a state post-catalysis but before the release of m6A. m6A occupies a novel evolutionarily conserved cryptic pocket in METTL3-METTL14 located ~16Å away from the SAM pocket that frequently mutates in cancer. We propose a two-step model of swiveling of target A upon conversion to m6A and sensing its methylation status by the cryptic pocket, enabling it to actuate enzymes' switch from writer to an m6A-sensor. Cancer-associated mutations cannot distinguish methylated from unmethylated adenine and show impaired RNA binding, de-stacking, and defective m6A writing and sensing.
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Affiliation(s)
- Shan Qi
- Greehey Children’s Cancer Research Institute, University of Texas Health Science Center at San Antonio, 8403 Floyd Curl Drive, San Antonio, TX 78229, USA
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA
| | - Yogesh K. Gupta
- Greehey Children’s Cancer Research Institute, University of Texas Health Science Center at San Antonio, 8403 Floyd Curl Drive, San Antonio, TX 78229, USA
- Department of Biochemistry and Structural Biology, University of Texas Health Science Center at San Antonio, 7703 Floyd Curl Drive, San Antonio, TX 78229, USA
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12
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Palumbo RJ, Hanes SD. Catalytic activity of the Bin3/MEPCE methyltransferase domain is dispensable for 7SK snRNP function in Drosophila melanogaster. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.06.01.543302. [PMID: 37333392 PMCID: PMC10274667 DOI: 10.1101/2023.06.01.543302] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/20/2023]
Abstract
Methylphosphate Capping Enzyme (MEPCE) monomethylates the gamma phosphate at the 5' end of the 7SK noncoding RNA, a modification thought to protect 7SK from degradation. 7SK serves as a scaffold for assembly of a snRNP complex that inhibits transcription by sequestering the positive elongation factor P-TEFb. While much is known about the biochemical activity of MEPCE in vitro, little is known about its functions in vivo, or what roles- if any-there are for regions outside the conserved methyltransferase domain. Here, we investigated the role of Bin3, the Drosophila ortholog of MEPCE, and its conserved functional domains in Drosophila development. We found that bin3 mutant females had strongly reduced rates of egg-laying, which was rescued by genetic reduction of P-TEFb activity, suggesting that Bin3 promotes fecundity by repressing P-TEFb. bin3 mutants also exhibited neuromuscular defects, analogous to a patient with MEPCE haploinsufficiency. These defects were also rescued by genetic reduction of P-TEFb activity, suggesting that Bin3 and MEPCE have conserved roles in promoting neuromuscular function by repressing P-TEFb. Unexpectedly, we found that a Bin3 catalytic mutant (Bin3Y795A) could still bind and stabilize 7SK and rescue all bin3 mutant phenotypes, indicating that Bin3 catalytic activity is dispensable for 7SK stability and snRNP function in vivo. Finally, we identified a metazoan-specific motif (MSM) outside of the methyltransferase domain and generated mutant flies lacking this motif (Bin3ΔMSM). Bin3ΔMSM mutant flies exhibited some-but not all-bin3 mutant phenotypes, suggesting that the MSM is required for a 7SK-independent, tissue-specific function of Bin3.
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Affiliation(s)
- Ryan J Palumbo
- Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University 750 East Adams Street, 4283 Weiskotten Hall, Syracuse, New York, 13210
| | - Steven D Hanes
- Department of Biochemistry & Molecular Biology, SUNY Upstate Medical University 750 East Adams Street, 4283 Weiskotten Hall, Syracuse, New York, 13210
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