1
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Wang Y, Li X, Chen X, Siewers V. CRISPR/Cas9-mediated point mutations improve α-amylase secretion in Saccharomyces cerevisiae. FEMS Yeast Res 2022; 22:6626025. [PMID: 35776981 PMCID: PMC9290899 DOI: 10.1093/femsyr/foac033] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2022] [Accepted: 06/28/2022] [Indexed: 11/12/2022] Open
Abstract
The rapid expansion of the application of pharmaceutical proteins and industrial enzymes requires robust microbial workhorses for high protein production. The budding yeast Saccharomyces cerevisiae is an attractive cell factory due to its ability to perform eukaryotic post-translational modifications and to secrete proteins. Many strategies have been used to engineer yeast platform strains for higher protein secretion capacity. Herein, we investigated a line of strains that have previously been selected after UV random mutagenesis for improved α-amylase secretion. A total of 42 amino acid altering point mutations identified in this strain line were reintroduced into the parental strain AAC to study their individual effects on protein secretion. These point mutations included missense mutations (amino acid substitution), nonsense mutations (stop codon generation), and frameshift mutations. For comparison, single gene deletions for the corresponding target genes were also performed in this study. A total of 11 point mutations and seven gene deletions were found to effectively improve α-amylase secretion. These targets were involved in several bioprocesses, including cellular stresses, protein degradation, transportation, mRNA processing and export, DNA replication, and repair, which indicates that the improved protein secretion capacity in the evolved strains is the result of the interaction of multiple intracellular processes. Our findings will contribute to the construction of novel cell factories for recombinant protein secretion.
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Affiliation(s)
- Yanyan Wang
- Department of Biology and Biological Engineering, Chalmers University of Technology, Kemivägen 10, SE-41296 Gothenburg, Sweden
| | - Xiaowei Li
- Department of Biology and Biological Engineering, Chalmers University of Technology, Kemivägen 10, SE-41296 Gothenburg, Sweden
| | - Xin Chen
- Department of Biology and Biological Engineering, Chalmers University of Technology, Kemivägen 10, SE-41296 Gothenburg, Sweden
- Novo Nordisk Foundation Center for Biosustainability, Chalmers University of Technology, Kemivägen 10, SE-41296 Gothenburg, Sweden
| | - Verena Siewers
- Corresponding author. Department of Biology and Biological Engineering, Chalmers University of Technology, Kemivägen 10, SE-41296 Gothenburg, Sweden. Tel: +46 (0)317723853; E-mail:
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2
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Soubise B, Jiang Y, Douet-Guilbert N, Troadec MB. RBM22, a Key Player of Pre-mRNA Splicing and Gene Expression Regulation, Is Altered in Cancer. Cancers (Basel) 2022; 14:cancers14030643. [PMID: 35158909 PMCID: PMC8833553 DOI: 10.3390/cancers14030643] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 01/19/2022] [Accepted: 01/22/2022] [Indexed: 01/05/2023] Open
Abstract
RNA-Binding Proteins (RBP) are very diverse and cover a large number of functions in the cells. This review focuses on RBM22, a gene encoding an RBP and belonging to the RNA-Binding Motif (RBM) family of genes. RBM22 presents a Zinc Finger like and a Zinc Finger domain, an RNA-Recognition Motif (RRM), and a Proline-Rich domain with a general structure suggesting a fusion of two yeast genes during evolution: Cwc2 and Ecm2. RBM22 is mainly involved in pre-mRNA splicing, playing the essential role of maintaining the conformation of the catalytic core of the spliceosome and acting as a bridge between the catalytic core and other essential protein components of the spliceosome. RBM22 is also involved in gene regulation, and is able to bind DNA, acting as a bona fide transcription factor on a large number of target genes. Undoubtedly due to its wide scope in the regulation of gene expression, RBM22 has been associated with several pathologies and, notably, with the aggressiveness of cancer cells and with the phenotype of a myelodysplastic syndrome. Mutations, enforced expression level, and haploinsufficiency of RBM22 gene are observed in those diseases. RBM22 could represent a potential therapeutic target in specific diseases, and, notably, in cancer.
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Affiliation(s)
- Benoît Soubise
- Université de Brest, Inserm, EFS, UMR 1078, GGB, F-29200 Brest, France; (B.S.); (Y.J.); (N.D.-G.)
| | - Yan Jiang
- Université de Brest, Inserm, EFS, UMR 1078, GGB, F-29200 Brest, France; (B.S.); (Y.J.); (N.D.-G.)
- Department of Hematology, The First Hospital of Jilin University, Changchun 130021, China
| | - Nathalie Douet-Guilbert
- Université de Brest, Inserm, EFS, UMR 1078, GGB, F-29200 Brest, France; (B.S.); (Y.J.); (N.D.-G.)
- CHRU Brest, Service de Génétique, Laboratoire de Génétique Chromosomique, F-29200 Brest, France
| | - Marie-Bérengère Troadec
- Université de Brest, Inserm, EFS, UMR 1078, GGB, F-29200 Brest, France; (B.S.); (Y.J.); (N.D.-G.)
- CHRU Brest, Service de Génétique, Laboratoire de Génétique Chromosomique, F-29200 Brest, France
- Correspondence: ; Tel.: +33-2-98-01-64-55
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3
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Liu X, Pan X, Chen D, Yin C, Peng J, Shi W, Qi L, Wang R, Zhao W, Zhang Z, Yang J, Peng YL. Prp19-associated splicing factor Cwf15 regulates fungal virulence and development in the rice blast fungus. Environ Microbiol 2021; 23:5901-5916. [PMID: 34056823 DOI: 10.1111/1462-2920.15616] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Revised: 05/26/2021] [Accepted: 05/27/2021] [Indexed: 11/29/2022]
Abstract
The splicing factor Cwf15 is an essential component of the Prp19-associated component of the spliceosome and regulates intron splicing in several model species, including yeasts and human cells. However, the roles of Cwf15 remain unexplored in plant pathogenic fungi. Here, we report that MoCWF15 in the rice blast fungus Magnaporthe oryzae is non-essential to viability and important to fungal virulence, growth and conidiation. MoCwf15 contains a putative nuclear localization signal (NLS) and is localized into the nucleus. The NLS sequence but not the predicted phosphorylation site or two sumoylation sites was essential for the biological functions of MoCwf15. Importantly, MoCwf15 physically interacted with the Prp19-associated splicing factors MoCwf4, MoSsa1 and MoCyp1, and negatively regulated protein accumulations of MoCyp1 and MoCwf4. Furthermore, with the deletion of MoCWF15, aberrant intron splicing occurred in near 400 genes, 20 of which were important to the fungal development and virulence. Taken together, MoCWF15 regulates fungal growth and infection-related development by modulating the intron splicing efficiency of a subset of genes in the rice blast fungus.
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Affiliation(s)
- Xinsen Liu
- Ministry of Agriculture and Rural Affairs Key Laboratory of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing, 100193, China
| | - Xiao Pan
- Ministry of Agriculture and Rural Affairs Key Laboratory of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing, 100193, China
| | - Deng Chen
- Ministry of Agriculture and Rural Affairs Key Laboratory of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing, 100193, China.,State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing, 100193, China
| | - Changfa Yin
- Ministry of Agriculture and Rural Affairs Key Laboratory of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing, 100193, China.,State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing, 100193, China
| | - Junbo Peng
- Ministry of Agriculture and Rural Affairs Key Laboratory of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing, 100193, China.,State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing, 100193, China
| | - Wei Shi
- Ministry of Agriculture and Rural Affairs Key Laboratory of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing, 100193, China.,State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing, 100193, China
| | - Linlu Qi
- Ministry of Agriculture and Rural Affairs Key Laboratory of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing, 100193, China
| | - Ruijin Wang
- Ministry of Agriculture and Rural Affairs Key Laboratory of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing, 100193, China.,Department of Plant Biosecurity, College of Plant Protection, China Agricultural University, Beijing, 100193, China
| | - Wensheng Zhao
- Ministry of Agriculture and Rural Affairs Key Laboratory of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing, 100193, China.,State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing, 100193, China.,Department of Plant Biosecurity, College of Plant Protection, China Agricultural University, Beijing, 100193, China
| | - Ziding Zhang
- State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing, 100193, China
| | - Jun Yang
- Ministry of Agriculture and Rural Affairs Key Laboratory of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing, 100193, China.,Department of Plant Biosecurity, College of Plant Protection, China Agricultural University, Beijing, 100193, China
| | - You-Liang Peng
- Ministry of Agriculture and Rural Affairs Key Laboratory of Pest Monitoring and Green Management, College of Plant Protection, China Agricultural University, Beijing, 100193, China.,State Key Laboratory of Agrobiotechnology, China Agricultural University, Beijing, 100193, China
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4
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Ciavarella J, Perea W, Greenbaum NL. Topology of the U12-U6 atac snRNA Complex of the Minor Spliceosome and Binding by NTC-Related Protein RBM22. ACS OMEGA 2020; 5:23549-23558. [PMID: 32984674 PMCID: PMC7512442 DOI: 10.1021/acsomega.0c01674] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 08/04/2020] [Indexed: 06/02/2023]
Abstract
Splicing of precursor messenger RNA is catalyzed by the spliceosome, a dynamic ribonucleoprotein assembly including five small nuclear (sn)RNAs and >100 proteins. RNA components catalyze the two transesterification reactions, but proteins perform critical roles in assembly and rearrangement. The catalytic core comprises a paired complex of U2 and U6 snRNAs for the major form of the spliceosome and U12 and U6atac snRNAs for the minor variant (∼0.3% of all spliceosomes in higher eukaryotes); the latter shares key catalytic sequence elements and performs identical chemistry. Here we use solution NMR techniques to show that the U12-U6atac snRNA complex of both human and Arabidopsis maintain base-pairing patterns similar to those in the three-helix model of the U2-U6 snRNA complex that position key elements to form the spliceosome's active site. However, in place of the stacked base pairs at the base of the U6 snRNA intramolecular stem loop and the central junction of the U2-U6 snRNA complex, we see altered geometry in the single-stranded hinge region opposing termini of the snRNAs to enable interaction between the key elements. We then use electrophoretic mobility shift assays and fluorescence assays to show that the protein RBM22, implicated in remodeling the human U2-U6 snRNA complex prior to catalysis, also binds the U12-U6atac snRNA complexes specifically and with similar affinity as to U2-U6 snRNA (a mean K d for the two methods = 3.4 and 8.0 μM for U2-U6 and U12-U6atac snRNA complexes, respectively), suggesting that RBM22 performs the same role in both spliceosomes.
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Affiliation(s)
- Joanna Ciavarella
- Ph.D.
Program in Chemistry, The Graduate Center
of the City University of New York, New York, New York 10016, United States
- Department
of Chemistry, Hunter College of the City
University of New York, New York, New York 10065, United States
| | - William Perea
- Department
of Chemistry, Hunter College of the City
University of New York, New York, New York 10065, United States
| | - Nancy L. Greenbaum
- Ph.D.
Program in Chemistry, The Graduate Center
of the City University of New York, New York, New York 10016, United States
- Ph.D.
Program in Biochemistry, The Graduate Center
of the City University of New York, New York, New York 10016, United States
- Department
of Chemistry, Hunter College of the City
University of New York, New York, New York 10065, United States
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5
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Abstract
Splicing of the precursor messenger RNA, involving intron removal and exon ligation, is mediated by the spliceosome. Together with biochemical and genetic investigations of the past four decades, structural studies of the intact spliceosome at atomic resolution since 2015 have led to mechanistic delineation of RNA splicing with remarkable insights. The spliceosome is proven to be a protein-orchestrated metalloribozyme. Conserved elements of small nuclear RNA (snRNA) constitute the splicing active site with two catalytic metal ions and recognize three conserved intron elements through duplex formation, which are delivered into the splicing active site for branching and exon ligation. The protein components of the spliceosome stabilize the conformation of the snRNA, drive spliceosome remodeling, orchestrate the movement of the RNA elements, and facilitate the splicing reaction. The overall organization of the spliceosome and the configuration of the splicing active site are strictly conserved between human and yeast.
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Affiliation(s)
- Ruixue Wan
- Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China;,
| | - Rui Bai
- Institute of Biology, Westlake Institute for Advanced Study, Westlake University, Hangzhou 310024, China
| | - Xiechao Zhan
- Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China;,
| | - Yigong Shi
- Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences and School of Medicine, Tsinghua University, Beijing 100084, China;,
- Institute of Biology, Westlake Institute for Advanced Study, Westlake University, Hangzhou 310024, China
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6
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Structures of the human spliceosomes before and after release of the ligated exon. Cell Res 2019; 29:274-285. [PMID: 30728453 PMCID: PMC6461851 DOI: 10.1038/s41422-019-0143-x] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2018] [Accepted: 01/14/2019] [Indexed: 11/08/2022] Open
Abstract
Pre-mRNA splicing is executed by the spliceosome, which has eight major functional states each with distinct composition. Five of these eight human spliceosomal complexes, all preceding exon ligation, have been structurally characterized. In this study, we report the cryo-electron microscopy structures of the human post-catalytic spliceosome (P complex) and intron lariat spliceosome (ILS) at average resolutions of 3.0 and 2.9 Å, respectively. In the P complex, the ligated exon remains anchored to loop I of U5 small nuclear RNA, and the 3′-splice site is recognized by the junction between the 5′-splice site and the branch point sequence. The ATPase/helicase Prp22, along with the ligated exon and eight other proteins, are dissociated in the P-to-ILS transition. Intriguingly, the ILS complex exists in two distinct conformations, one with the ATPase/helicase Prp43 and one without. Comparison of these three late-stage human spliceosomes reveals mechanistic insights into exon release and spliceosome disassembly.
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7
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Cryo-EM structure of the spliceosome immediately after branching. Nature 2016; 537:197-201. [PMID: 27459055 PMCID: PMC5156311 DOI: 10.1038/nature19316] [Citation(s) in RCA: 177] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 07/19/2016] [Indexed: 12/11/2022]
Abstract
Precursor mRNA (pre-mRNA) splicing proceeds by two consecutive transesterification reactions via a lariat-intron intermediate. Here we present the 3.8 Å cryo-electron microscopy structure of the spliceosome immediately after lariat formation. The 5'-splice site is cleaved but remains close to the catalytic Mg2+ site in the U2/U6 small nuclear RNA (snRNA) triplex, and the 5'-phosphate of the intron nucleotide G(+1) is linked to the branch adenosine 2'OH. The 5'-exon is held between the Prp8 amino-terminal and linker domains, and base-pairs with U5 snRNA loop 1. Non-Watson-Crick interactions between the branch helix and 5'-splice site dock the branch adenosine into the active site, while intron nucleotides +3 to +6 base-pair with the U6 snRNA ACAGAGA sequence. Isy1 and the step-one factors Yju2 and Cwc25 stabilize docking of the branch helix. The intron downstream of the branch site emerges between the Prp8 reverse transcriptase and linker domains and extends towards the Prp16 helicase, suggesting a plausible mechanism of remodelling before exon ligation.
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8
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Collier SE, Voehler M, Peng D, Ohi R, Gould KL, Reiter NJ, Ohi MD. Structural and functional insights into the N-terminus of Schizosaccharomyces pombe Cdc5. Biochemistry 2014; 53:6439-51. [PMID: 25263959 PMCID: PMC4204884 DOI: 10.1021/bi5008639] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
![]()
The
spliceosome is a dynamic macromolecular machine composed of
five small nuclear ribonucleoparticles (snRNPs), the NineTeen Complex
(NTC), and other proteins that catalyze the removal of introns mature
to form the mature message. The NTC, named after its founding member Saccharomyces cerevisiae Prp19, is a conserved spliceosome
subcomplex composed of at least nine proteins. During spliceosome
assembly, the transition to an active spliceosome correlates with
stable binding of the NTC, although the mechanism of NTC function
is not understood. Schizosaccharomyces pombe Cdc5, a core subunit of the NTC, is an essential protein required
for pre-mRNA splicing. The highly conserved Cdc5 N-terminus contains
two canonical Myb (myeloblastosis) repeats (R1 and R2) and a third
domain (D3) that was previously classified as a Myb-like repeat. Although
the N-terminus of Cdc5 is required for its function, how R1, R2, and
D3 each contribute to functionality is unclear. Using a combination
of yeast genetics, structural approaches, and RNA binding assays,
we show that R1, R2, and D3 are all required for the function of Cdc5
in cells. We also show that the N-terminus of Cdc5 binds RNA in vitro. Structural and functional analyses of Cdc5-D3
show that, while this domain does not adopt a Myb fold, Cdc5-D3 preferentially
binds double-stranded RNA. Our data suggest that the Cdc5 N-terminus
interacts with RNA structures proposed to be near the catalytic core
of the spliceosome.
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Affiliation(s)
- Scott E Collier
- Department of Cell and Developmental Biology, Vanderbilt University Medical Center , Nashville, Tennessee 37232, United States
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9
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Hogg R, de Almeida RA, Ruckshanthi JPD, O'Keefe RT. Remodeling of U2-U6 snRNA helix I during pre-mRNA splicing by Prp16 and the NineTeen Complex protein Cwc2. Nucleic Acids Res 2014; 42:8008-23. [PMID: 24848011 PMCID: PMC4081067 DOI: 10.1093/nar/gku431] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Removal of intron regions from pre-messenger RNA (pre-mRNA) requires spliceosome assembly with pre-mRNA, then subsequent spliceosome remodeling to allow activation for the two steps of intron removal. Spliceosome remodeling is carried out through the action of DExD/H-box ATPases that modulate RNA-RNA and protein-RNA interactions. The ATPase Prp16 remodels the spliceosome between the first and second steps of splicing by catalyzing release of first step factors Yju2 and Cwc25 as well as destabilizing U2-U6 snRNA helix I. How Prp16 destabilizes U2-U6 helix I is not clear. We show that the NineTeen Complex (NTC) protein Cwc2 displays genetic interactions with the U6 ACAGAGA, the U6 internal stem loop (ISL) and the U2-U6 helix I, all RNA elements that form the spliceosome active site. We find that one function of Cwc2 is to stabilize U2-U6 snRNA helix I during splicing. Cwc2 also functionally cooperates with the NTC protein Isy1/NTC30. Mutation in Cwc2 can suppress the cold sensitive phenotype of the prp16-302 mutation indicating a functional link between Cwc2 and Prp16. Specifically the prp16-302 mutation in Prp16 stabilizes Cwc2 interactions with U6 snRNA and destabilizes Cwc2 interactions with pre-mRNA, indicating antagonistic functions of Cwc2 and Prp16. We propose that Cwc2 is a target for Prp16-mediated spliceosome remodeling during pre-mRNA splicing.
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Affiliation(s)
- Rebecca Hogg
- Faculty of Life Sciences, The University of Manchester, Oxford Road, Manchester, M13 9PT
| | | | | | - Raymond T O'Keefe
- Faculty of Life Sciences, The University of Manchester, Oxford Road, Manchester, M13 9PT
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10
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Galej WP, Nguyen THD, Newman AJ, Nagai K. Structural studies of the spliceosome: zooming into the heart of the machine. Curr Opin Struct Biol 2014; 25:57-66. [PMID: 24480332 PMCID: PMC4045393 DOI: 10.1016/j.sbi.2013.12.002] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Revised: 12/09/2013] [Accepted: 12/11/2013] [Indexed: 11/30/2022]
Abstract
Spliceosomes are large, dynamic ribonucleoprotein complexes that catalyse the removal of introns from messenger RNA precursors via a two-step splicing reaction. The recent crystal structure of Prp8 has revealed Reverse Transcriptase-like, Linker and Endonuclease-like domains. The intron branch-point cross-link with the Linker domain of Prp8 in active spliceosomes and together with suppressors of 5' and 3' splice site mutations this unambiguously locates the active site cavity. Structural and mechanistic similarities with group II self-splicing introns have encouraged the notion that the spliceosome is at heart a ribozyme, and recently the ligands for two catalytic magnesium ions were identified within U6 snRNA. They position catalytic divalent metal ions in the same way as Domain V of group II intron RNA, suggesting that the spliceosome and group II intron use the same catalytic mechanisms.
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Affiliation(s)
- Wojciech P Galej
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, United Kingdom.
| | - Thi Hoang Duong Nguyen
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, United Kingdom
| | - Andrew J Newman
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, United Kingdom
| | - Kiyoshi Nagai
- MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge CB2 0QH, United Kingdom.
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11
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Esperante SA, Noval MG, Altieri TA, de Oliveira GAP, Silva JL, de Prat-Gay G. Fine modulation of the respiratory syncytial virus M2-1 protein quaternary structure by reversible zinc removal from its Cys(3)-His(1) motif. Biochemistry 2013; 52:6779-89. [PMID: 23984912 DOI: 10.1021/bi401029q] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Human respiratory syncytial virus (hRSV) is a worldwide distributed pathogen that causes respiratory disease mostly in infants and the elderly. The M2-1 protein of hRSV functions as a transcription antiterminator and partakes in virus particle budding. It is present only in Pneumovirinae, namely, Pneumovirus (RSV) and Metapneumovirus, making it an interesting target for specific antivirals. hRSV M2-1 is a tight tetramer bearing a Cys3-His1 zinc-binding motif, present in Ebola VP30 protein and some eukaryotic proteins, whose integrity was shown to be essential for protein function but without a biochemical mechanistic basis. We showed that removal of the zinc atom causes dissociation to a monomeric apo-M2-1 species. Surprisingly, the secondary structure and stability of the apo-monomer is indistinguishable from that of the M2-1 tetramer. Dissociation reported by a highly sensitive tryptophan residue is much increased at pH 5.0 compared to pH 7.0, suggesting a histidine protonation cooperating in zinc removal. The monomeric apo form binds RNA at least as well as the tetramer, and this interaction is outcompeted by the phosphoprotein P, the RNA polymerase cofactor. The role of zinc goes beyond stabilization of local structure, finely tuning dissociation to a fully folded and binding competent monomer. Removal of zinc is equivalent to the disruption of the motif by mutation, only that the former is potentially reversible in the cellular context. Thus, this process could be triggered by a natural chelator such as glutathione or thioneins, where reversibility strongly suggests a modulatory role in the participation of M2-1 in the assembly of the polymerase complex or in virion budding.
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Affiliation(s)
- Sebastián A Esperante
- Protein Structure-Function and Engineering Laboratory, Fundación Instituto Leloir and IIBA-Conicet , Patricias Argentinas 435, (1405) Buenos Aires, Argentina
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12
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Schmitzová J, Pena V. Emerging views about the molecular structure of the spliceosomal catalytic center. RNA Biol 2012; 9:1311-8. [PMID: 23064115 DOI: 10.4161/rna.22359] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Pre-mRNA splicing occurs in two chemical steps that are catalyzed by a large, dynamic RNA-protein complex called the spliceosome. Initially assembled in a catalytically inactive form, the spliceosome undergoes massive compositional and conformational remodeling, through which disparate RNA elements are re-configured and juxtaposed into a functional catalytic center. The intricate construction of the catalytic center requires the assistance of spliceosomal proteins. Recent structure-function analyses have demonstrated that the yeast-splicing factor Cwc2 is a main player that contacts and shapes the catalytic center of the spliceosome into a functional conformation. With this advance, corroborated by the atomic structure of the evolutionarily related group IIC introns, our understanding of the organization and formation of the spliceosomal catalytic center has progressed to a new level.
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Affiliation(s)
- Jana Schmitzová
- Department of Cellular Biochemistry, Max Planck Institute for Biophysical, Macromolecular Crystallography Group, Göttingen, Germany
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13
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Crystal structure of Cwc2 reveals a novel architecture of a multipartite RNA-binding protein. EMBO J 2012; 31:2222-34. [PMID: 22407296 DOI: 10.1038/emboj.2012.58] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2011] [Accepted: 02/14/2012] [Indexed: 11/08/2022] Open
Abstract
The yeast splicing factor Cwc2 contacts several catalytically important RNA elements in the active spliceosome, suggesting that Cwc2 is involved in determining their spatial arrangement at the spliceosome's catalytic centre. We have determined the crystal structure of the Cwc2 functional core, revealing how a previously uncharacterized Torus domain, an RNA recognition motif (RRM) and a zinc finger (ZnF) are tightly integrated in a compact folding unit. The ZnF plays a pivotal role in the architecture of the whole assembly. UV-induced crosslinking of Cwc2-U6 snRNA allowed the identification by mass spectrometry of six RNA-contacting sites: four in or close to the RRM domain, one in the ZnF and one on a protruding element connecting the Torus and RRM domains. The three distinct regions contacting RNA are connected by a contiguous and conserved positively charged surface, suggesting an expanded interface for RNA accommodation. Cwc2 mutations confirmed that the connector element plays a crucial role in splicing. We conclude that Cwc2 acts as a multipartite RNA-binding platform to bring RNA elements of the spliceosome's catalytic centre into an active conformation.
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