1
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Li Y, Liu C, Jia X, Bi L, Ren Z, Zhao Y, Zhang X, Guo L, Bao Y, Liu C, Li W, Sun B. RPA transforms RNase H1 to a bidirectional exoribonuclease for processive RNA-DNA hybrid cleavage. Nat Commun 2024; 15:7464. [PMID: 39198528 PMCID: PMC11358518 DOI: 10.1038/s41467-024-51984-5] [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: 01/04/2024] [Accepted: 08/21/2024] [Indexed: 09/01/2024] Open
Abstract
RNase H1 has been acknowledged as an endoribonuclease specializing in the internal degradation of the RNA moiety within RNA-DNA hybrids, and its ribonuclease activity is indispensable in multifaceted aspects of nucleic acid metabolism. However, the molecular mechanism underlying RNase H1-mediated hybrid cleavage remains inadequately elucidated. Herein, using single-molecule approaches, we probe the dynamics of the hybrid cleavage by Saccharomyces cerevisiae RNase H1. Remarkably, a single RNase H1 enzyme displays 3'-to-5' exoribonuclease activity. The directional RNA degradation proceeds processively and yet discretely, wherein unwinding approximately 6-bp hybrids as a prerequisite for two consecutive 3-nt RNA excisions limits the overall rate within each catalytic cycle. Moreover, Replication Protein A (RPA) reinforces RNase H1's 3'-to-5' nucleolytic rate and processivity and stimulates its 5'-to-3' exoribonuclease activity. This stimulation is primarily realized through the pre-separation of the hybrids and consequently transfers RNase H1 to a bidirectional exoribonuclease, further potentiating its cleavage efficiency. These findings unveil unprecedented characteristics of an RNase and provide a dynamic view of RPA-enhanced processive hybrid cleavage by RNase H1.
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Affiliation(s)
- Yanan Li
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Chao Liu
- Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, China
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Xinshuo Jia
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Lulu Bi
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Zhiyun Ren
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yilin Zhao
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Xia Zhang
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Lijuan Guo
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Yanling Bao
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China
| | - Cong Liu
- Interdisciplinary Research Center on Biology and Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, China
| | - Wei Li
- Guangzhou Women and Children's Medical Center, Guangzhou Medical University, Guangzhou, China.
- State Key Laboratory of Stem Cell and Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.
- University of Chinese Academy of Sciences, Beijing, China.
| | - Bo Sun
- School of Life Science and Technology, ShanghaiTech University, Shanghai, China.
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2
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Knappeová B, Mlýnský V, Pykal M, Šponer J, Banáš P, Otyepka M, Krepl M. Comprehensive Assessment of Force-Field Performance in Molecular Dynamics Simulations of DNA/RNA Hybrid Duplexes. J Chem Theory Comput 2024; 20:6917-6929. [PMID: 39012172 PMCID: PMC11325551 DOI: 10.1021/acs.jctc.4c00601] [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: 07/17/2024]
Abstract
Mixed double helices formed by RNA and DNA strands, commonly referred to as hybrid duplexes or hybrids, are essential in biological processes like transcription and reverse transcription. They are also important for their applications in CRISPR gene editing and nanotechnology. Yet, despite their significance, the hybrid duplexes have been seldom modeled by atomistic molecular dynamics methodology, and there is no benchmark study systematically assessing the force-field performance. Here, we present an extensive benchmark study of polypurine tract (PPT) and Dickerson-Drew dodecamer hybrid duplexes using contemporary and commonly utilized pairwise additive and polarizable nucleic acid force fields. Our findings indicate that none of the available force-field choices accurately reproduces all the characteristic structural details of the hybrid duplexes. The AMBER force fields are unable to populate the C3'-endo (north) pucker of the DNA strand and underestimate inclination. The CHARMM force field accurately describes the C3'-endo pucker and inclination but shows base pair instability. The polarizable force fields struggle with accurately reproducing the helical parameters. Some force-field combinations even demonstrate a discernible conflict between the RNA and DNA parameters. In this work, we offer a candid assessment of the force-field performance for mixed DNA/RNA duplexes. We provide guidance on selecting utilizable force-field combinations and also highlight potential pitfalls and best practices for obtaining optimal performance.
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Affiliation(s)
- Barbora Knappeová
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, Brno 612 00, Czech Republic
| | - Vojtěch Mlýnský
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, Brno 612 00, Czech Republic
| | - Martin Pykal
- Czech Advanced Technology and Research Institute, CATRIN, Palacký University, Křížkovského 511/8, Olomouc 779 00, Czech Republic
| | - Jiří Šponer
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, Brno 612 00, Czech Republic
| | - Pavel Banáš
- Czech Advanced Technology and Research Institute, CATRIN, Palacký University, Křížkovského 511/8, Olomouc 779 00, Czech Republic
| | - Michal Otyepka
- Czech Advanced Technology and Research Institute, CATRIN, Palacký University, Křížkovského 511/8, Olomouc 779 00, Czech Republic
- IT4Innovations, VSB-Technical University of Ostrava, 17. listopadu 2172/15, Ostrava-Poruba 708 00, Czech Republic
| | - Miroslav Krepl
- Institute of Biophysics of the Czech Academy of Sciences, Královopolská 135, Brno 612 00, Czech Republic
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3
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Fakharzadeh A, Qu J, Pan F, Sagui C, Roland C. Structure and Dynamics of DNA and RNA Double Helices Formed by d(CTG), d(GTC), r(CUG), and r(GUC) Trinucleotide Repeats and Associated DNA-RNA Hybrids. J Phys Chem B 2023; 127:7907-7924. [PMID: 37681731 PMCID: PMC10519205 DOI: 10.1021/acs.jpcb.3c03538] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 07/11/2023] [Indexed: 09/09/2023]
Abstract
Myotonic dystrophy type 1 is the most frequent form of muscular dystrophy in adults caused by an abnormal expansion of the CTG trinucleotide. Both the expanded DNA and the expanded CUG RNA transcript can fold into hairpins. Co-transcriptional formation of stable RNA·DNA hybrids can also enhance the instability of repeat tracts. We performed molecular dynamics simulations of homoduplexes associated with the disease, d(CTG)n and r(CUG)n, and their corresponding r(CAG)n:d(CTG)n and r(CUG)n:d(CAG)n hybrids that can form under bidirectional transcription and of non-pathological d(GTC)n and d(GUC)n homoduplexes. We characterized their conformations, stability, and dynamics and found that the U·U and T·T mismatches are dynamic, favoring anti-anti conformations inside the helical core, followed by anti-syn and syn-syn conformations. For DNA, the secondary minima in the non-expanding d(GTC)n helices are deeper, wider, and longer-lived than those in d(CTG)n, which constitutes another biophysical factor further differentiating the expanding and non-expanding sequences. The hybrid helices are closer to A-RNA, with the A-T and A-U pairs forming two stable Watson-Crick hydrogen bonds. The neutralizing ion distribution around the non-canonical pairs is also described.
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Affiliation(s)
- Ashkan Fakharzadeh
- Department
of Physics, North Carolina State University, Raleigh, North Carolina 27695-8202, USA
| | - Jing Qu
- Department
of Physics, North Carolina State University, Raleigh, North Carolina 27695-8202, USA
| | - Feng Pan
- Department
of Statistics, Florida State University, Tallahassee, Florida 32306, USA
| | - Celeste Sagui
- Department
of Physics, North Carolina State University, Raleigh, North Carolina 27695-8202, USA
| | - Christopher Roland
- Department
of Physics, North Carolina State University, Raleigh, North Carolina 27695-8202, USA
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4
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Jhan CR, Satange R, Wang SC, Zeng JY, Horng YC, Jin P, Neidle S, Hou MH. Targeting the ALS/FTD-associated A-DNA kink with anthracene-based metal complex causes DNA backbone straightening and groove contraction. Nucleic Acids Res 2021; 49:9526-9538. [PMID: 33836081 PMCID: PMC8450080 DOI: 10.1093/nar/gkab227] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 03/16/2021] [Accepted: 03/26/2021] [Indexed: 12/22/2022] Open
Abstract
The use of a small molecule compound to reduce toxic repeat RNA transcripts or their translated aberrant proteins to target repeat-expanded RNA/DNA with a G4C2 motif is a promising strategy to treat C9orf72-linked disorders. In this study, the crystal structures of DNA and RNA–DNA hybrid duplexes with the -GGGCCG- region as a G4C2 repeat motif were solved. Unusual groove widening and sharper bending of the G4C2 DNA duplex A-DNA conformation with B-form characteristics inside was observed. The G4C2 RNA–DNA hybrid duplex adopts a more typical rigid A form structure. Detailed structural analysis revealed that the G4C2 repeat motif of the DNA duplex exhibits a hydration shell and greater flexibility and serves as a ‘hot-spot’ for binding of the anthracene-based nickel complex, NiII(Chro)2 (Chro = Chromomycin A3). In addition to the original GGCC recognition site, NiII(Chro)2 has extended specificity and binds the flanked G:C base pairs of the GGCC core, resulting in minor groove contraction and straightening of the DNA backbone. We have also shown that Chro-metal complexes inhibit neuronal toxicity and suppresses locomotor deficits in a Drosophila model of C9orf72-associated ALS. The approach represents a new direction for drug discovery against ALS and FTD diseases by targeting G4C2 repeat motif DNA.
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Affiliation(s)
- Cyong-Ru Jhan
- Department of Life Sciences, National Chung-Hsing University, Taichung 402, Taiwan
| | - Roshan Satange
- Ph.D. Program in Medical Biotechnology, National Chung Hsing University, Taichung 402, Taiwan.,Institute of Genomics and Bioinformatics; National Chung Hsing University, Taichung 402, Taiwan
| | - Shun-Ching Wang
- Institute of Genomics and Bioinformatics; National Chung Hsing University, Taichung 402, Taiwan
| | - Jing-Yi Zeng
- Institute of Genomics and Bioinformatics; National Chung Hsing University, Taichung 402, Taiwan
| | - Yih-Chern Horng
- Department of Chemistry, National Changhua University of Education, Changhua 50058, Taiwan
| | - Peng Jin
- Department of Human Genetics, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Stephen Neidle
- The School of Pharmacy, University College London, London, WC1N 1AX, United Kingdom
| | - Ming-Hon Hou
- Department of Life Sciences, National Chung-Hsing University, Taichung 402, Taiwan.,Ph.D. Program in Medical Biotechnology, National Chung Hsing University, Taichung 402, Taiwan.,Institute of Genomics and Bioinformatics; National Chung Hsing University, Taichung 402, Taiwan
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5
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Chen JL, Zhang P, Abe M, Aikawa H, Zhang L, Frank AJ, Zembryski T, Hubbs C, Park H, Withka J, Steppan C, Rogers L, Cabral S, Pettersson M, Wager TT, Fountain MA, Rumbaugh G, Childs-Disney JL, Disney MD. Design, Optimization, and Study of Small Molecules That Target Tau Pre-mRNA and Affect Splicing. J Am Chem Soc 2020; 142:8706-8727. [PMID: 32364710 PMCID: PMC7357857 DOI: 10.1021/jacs.0c00768] [Citation(s) in RCA: 34] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Approximately 95% of human genes are alternatively spliced, and aberrant splicing events can cause disease. One pre-mRNA that is alternatively spliced and linked to neurodegenerative diseases is tau (microtubule-associated protein tau), which can cause frontotemporal dementia and parkinsonism linked to chromosome 17 (FTDP-17) and can contribute to Alzheimer's disease. Here, we describe the design of structure-specific lead small molecules that directly target tau pre-mRNA from sequence. This was followed by hit expansion and analogue synthesis to further improve upon these initial lead molecules. The emergent compounds were assessed for functional activity in a battery of assays, including binding assays and an assay that mimics molecular recognition of tau pre-mRNA by a U1 small nuclear ribonucleoprotein (snRNP) splicing factor. Compounds that emerged from these studies had enhanced potency and selectivity for the target RNA relative to the initial hits, while also having significantly improved drug-like properties. The compounds are shown to directly target tau pre-mRNA in cells, via chemical cross-linking and isolation by pull-down target profiling, and to rescue disease-relevant splicing of tau pre-mRNA in a variety of cellular systems, including primary neurons. More broadly, this study shows that lead, structure-specific compounds can be designed from sequence and then further optimized for their physicochemical properties while at the same time enhancing their activity.
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Affiliation(s)
- Jonathan L. Chen
- Department of Chemistry and Neuroscience, The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Peiyuan Zhang
- Department of Chemistry and Neuroscience, The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Masahito Abe
- Department of Chemistry and Neuroscience, The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Haruo Aikawa
- Department of Chemistry and Neuroscience, The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Liying Zhang
- Pfizer Worldwide Research and Development, Cambridge, Massachusetts 02139, United States
| | - Alexander J. Frank
- Department of Chemistry & Biochemistry, State University of New York at Fredonia, Fredonia, New York 14063, United States
| | - Timothy Zembryski
- Department of Chemistry & Biochemistry, State University of New York at Fredonia, Fredonia, New York 14063, United States
| | - Christopher Hubbs
- Department of Chemistry and Neuroscience, The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - HaJeung Park
- Department of Chemistry and Neuroscience, The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Jane Withka
- Pfizer Worldwide Research and Development, Cambridge, Massachusetts 02139, United States
| | - Claire Steppan
- Pfizer Worldwide Research and Development, Groton, Connecticut 06340, United States
| | - Lucy Rogers
- Pfizer Worldwide Research and Development, Groton, Connecticut 06340, United States
| | - Shawn Cabral
- Pfizer Worldwide Research and Development, Groton, Connecticut 06340, United States
| | - Martin Pettersson
- Pfizer Worldwide Research and Development, Cambridge, Massachusetts 02139, United States
| | - Travis T. Wager
- Pfizer Worldwide Research and Development, Cambridge, Massachusetts 02139, United States
| | - Matthew A. Fountain
- Department of Chemistry & Biochemistry, State University of New York at Fredonia, Fredonia, New York 14063, United States
| | - Gavin Rumbaugh
- Department of Chemistry and Neuroscience, The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Jessica L. Childs-Disney
- Department of Chemistry and Neuroscience, The Scripps Research Institute, Jupiter, Florida 33458, United States
| | - Matthew D. Disney
- Department of Chemistry and Neuroscience, The Scripps Research Institute, Jupiter
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6
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Liu JH, Xi K, Zhang X, Bao L, Zhang X, Tan ZJ. Structural Flexibility of DNA-RNA Hybrid Duplex: Stretching and Twist-Stretch Coupling. Biophys J 2019; 117:74-86. [PMID: 31164196 PMCID: PMC6626833 DOI: 10.1016/j.bpj.2019.05.018] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 04/25/2019] [Accepted: 05/17/2019] [Indexed: 12/21/2022] Open
Abstract
DNA-RNA hybrid (DRH) duplexes play essential roles during the replication of DNA and the reverse transcription of RNA viruses, and their flexibility is important for their biological functions. Recent experiments indicated that A-form RNA and B-form DNA have a strikingly different flexibility in stretching and twist-stretch coupling, and the structural flexibility of DRH duplex is of great interest, especially in stretching and twist-stretch coupling. In this work, we performed microsecond all-atom molecular dynamics simulations with new AMBER force fields to characterize the structural flexibility of DRH duplex in stretching and twist-stretch coupling. We have calculated all the helical parameters, stretch modulus, and twist-stretch coupling parameters for the DRH duplex. First, our analyses on structure suggest that the DRH duplex exhibits an intermediate conformation between A- and B-forms and closer to A-form, which can be attributed to the stronger rigidity of the RNA strand than the DNA strand. Second, our calculations show that the DRH duplex has the stretch modulus of 834 ± 34 pN and a very weak twist-stretch coupling. Our quantitative analyses indicate that, compared with DNA and RNA duplexes, the different flexibility of the DRH duplex in stretching and twist-stretch coupling is mainly attributed to its apparently different basepair inclination in the helical structure.
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Affiliation(s)
- Ju-Hui Liu
- Center for Theoretical Physics and Key Laboratory of Artificial Micro- & Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, China
| | - Kun Xi
- Center for Theoretical Physics and Key Laboratory of Artificial Micro- & Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, China
| | - Xi Zhang
- Center for Theoretical Physics and Key Laboratory of Artificial Micro- & Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, China
| | - Lei Bao
- Center for Theoretical Physics and Key Laboratory of Artificial Micro- & Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, China
| | - Xinghua Zhang
- College of Life Science, the Institute for Advanced Studies, State Key Laboratory of Virology, Hubei Key Laboratory of Cell Homeostasis, Wuhan University, Wuhan, China.
| | - Zhi-Jie Tan
- Center for Theoretical Physics and Key Laboratory of Artificial Micro- & Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan, China.
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7
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Kamble NR, Sigurdsson ST. Purine-Derived Nitroxides for Noncovalent Spin-Labeling of Abasic Sites in Duplex Nucleic Acids. Chemistry 2018; 24:4157-4164. [DOI: 10.1002/chem.201705410] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Indexed: 12/27/2022]
Affiliation(s)
- Nilesh R. Kamble
- University of Iceland; Department of Chemistry; Science Institute; Dunhaga 3 107 Reykjavik Iceland
| | - Snorri Th. Sigurdsson
- University of Iceland; Department of Chemistry; Science Institute; Dunhaga 3 107 Reykjavik Iceland
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8
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Davis RR, Shaban NM, Perrino FW, Hollis T. Crystal structure of RNA-DNA duplex provides insight into conformational changes induced by RNase H binding. Cell Cycle 2015; 14:668-73. [PMID: 25664393 DOI: 10.4161/15384101.2014.994996] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
RNA-DNA hybrids play essential roles in a variety of biological processes, including DNA replication, transcription, and viral integration. Ribonucleotides incorporated within DNA are hydrolyzed by RNase H enzymes in a removal process that is necessary for maintaining genomic stability. In order to understand the structural determinants involved in recognition of a hybrid substrate by RNase H we have determined the crystal structure of a dodecameric non-polypurine/polypyrimidine tract RNA-DNA duplex. A comparison to the same sequence bound to RNase H, reveals structural changes to the duplex that include widening of the major groove to 12.5 Å from 4.2 Å and decreasing the degree of bending along the axis which may play a crucial role in the ribonucleotide recognition and cleavage mechanism within RNase H. This structure allows a direct comparison to be made about the conformational changes induced in RNA-DNA hybrids upon binding to RNase H and may provide insight into how dysfunction in the endonuclease causes disease.
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Affiliation(s)
- Ryan R Davis
- a Department of Biochemistry; Center for Structural Biology ; Wake Forest School of Medicine ; Winston-Salem , NC USA
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9
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Suresh G, Priyakumar UD. DNA–RNA hybrid duplexes with decreasing pyrimidine content in the DNA strand provide structural snapshots for the A- to B-form conformational transition of nucleic acids. Phys Chem Chem Phys 2014; 16:18148-55. [DOI: 10.1039/c4cp02478h] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
A gradual increase in the deoxypyrimidine content in DNA–RNA hybrids leads to B- to A-form nucleic acid transition. Possible factors that govern nuclease activity on hybrid duplexes are presented.
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Affiliation(s)
- Gorle Suresh
- Centre for Computational Natural Sciences and Bioinformatics
- International Institute of Information Technology
- Hyderabad 500 032, India
| | - U. Deva Priyakumar
- Centre for Computational Natural Sciences and Bioinformatics
- International Institute of Information Technology
- Hyderabad 500 032, India
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10
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Probing complexes with single fluorophores: factors contributing to dispersion of FRET in DNA/RNA duplexes. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2008; 38:395-405. [DOI: 10.1007/s00249-008-0383-z] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2008] [Revised: 10/23/2008] [Accepted: 10/23/2008] [Indexed: 10/21/2022]
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11
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Zhao H, Sohail A, Sun Q, Shi Q, Kim S, Mobashery S, Fridman R. Identification and role of the homodimerization interface of the glycosylphosphatidylinositol-anchored membrane type 6 matrix metalloproteinase (MMP25). J Biol Chem 2008; 283:35023-32. [PMID: 18936094 DOI: 10.1074/jbc.m806553200] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The membrane type (MT) 6 matrix metalloproteinase (MMP) (MMP25) is a glycosylphosphatidylinositol-anchored matrix metalloproteinase (MMP) that is highly expressed in leukocytes and in some cancer tissues. We previously showed that natural MT6-MMP is expressed on the cell surface as a major reduction-sensitive form of M(r) 120, likely representing enzyme homodimers held by disulfide bridges. Among the membrane type-MMPs, the stem region of MT6-MMP contains three cysteine residues at positions 530, 532, and 534 which may contribute to dimerization. A systematic site-directed mutagenesis study of the Cys residues in the stem region shows that Cys(532) is involved in MT6-MMP dimerization by forming an intermolecular disulfide bond. The mutagenesis data also suggest that Cys(530) and Cys(534) form an intramolecular disulfide bond. The experimental observations on cysteines were also investigated by computational studies of the stem peptide, which validate these proposals. Dimerization is not essential for transport of MT6-MMP to the cell surface, partitioning into lipid rafts or cleavage of alpha-1-proteinase inhibitor. However, monomeric forms of MT6-MMP exhibited enhanced autolysis and metalloprotease-dependent degradation. Collectively, these studies establish the stem region of MT6-MMP as the dimerization interface, an event whose outcome imparts protease stability to the protein.
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Affiliation(s)
- Huiren Zhao
- Department of Pathology, Wayne State University and Proteases and Cancer Program, Barbara Ann Karmanos Cancer Institute, Detroit, Michigan 48201, USA
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12
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Mura C, McCammon JA. Molecular dynamics of a kappaB DNA element: base flipping via cross-strand intercalative stacking in a microsecond-scale simulation. Nucleic Acids Res 2008; 36:4941-55. [PMID: 18653524 PMCID: PMC2528173 DOI: 10.1093/nar/gkn473] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The sequence-dependent structural variability and conformational dynamics of DNA play pivotal roles in many biological milieus, such as in the site-specific binding of transcription factors to target regulatory elements. To better understand DNA structure, function, and dynamics in general, and protein···DNA recognition in the ‘κB’ family of genetic regulatory elements in particular, we performed molecular dynamics simulations of a 20-bp DNA encompassing a cognate κB site recognized by the proto-oncogenic ‘c-Rel’ subfamily of NF-κB transcription factors. Simulations of the κB DNA in explicit water were extended to microsecond duration, providing a broad, atomically detailed glimpse into the structural and dynamical behavior of double helical DNA over many timescales. Of particular note, novel (and structurally plausible) conformations of DNA developed only at the long times sampled in this simulation—including a peculiar state arising at ≈0.7 μs and characterized by cross-strand intercalative stacking of nucleotides within a longitudinally sheared base pair, followed (at ≈1 μs) by spontaneous base flipping of a neighboring thymine within the A-rich duplex. Results and predictions from the microsecond-scale simulation include implications for a dynamical NF-κB recognition motif, and are amenable to testing and further exploration via specific experimental approaches that are suggested herein.
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Affiliation(s)
- Cameron Mura
- Department of Chemistry and Biochemistry and Center for Theoretical Biological Physics, University of California, San Diego, La Jolla, CA 92093-0365, USA.
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13
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Schultz SJ, Champoux JJ. RNase H activity: structure, specificity, and function in reverse transcription. Virus Res 2008; 134:86-103. [PMID: 18261820 DOI: 10.1016/j.virusres.2007.12.007] [Citation(s) in RCA: 99] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2007] [Revised: 12/13/2007] [Accepted: 12/13/2007] [Indexed: 01/20/2023]
Abstract
This review compares the well-studied RNase H activities of human immunodeficiency virus, type 1 (HIV-1) and Moloney murine leukemia virus (MoMLV) reverse transcriptases. The RNase H domains of HIV-1 and MoMLV are structurally very similar, with functions assigned to conserved subregions like the RNase H primer grip and the connection subdomain, as well as to distinct features like the C-helix and loop in MoMLV RNase H. Like cellular RNases H, catalysis by the retroviral enzymes appears to involve a two-metal ion mechanism. Unlike cellular RNases H, the retroviral RNases H display three different modes of cleavage: internal, DNA 3' end-directed, and RNA 5' end-directed. All three modes of cleavage appear to have roles in reverse transcription. Nucleotide sequence is an important determinant of cleavage specificity with both enzymes exhibiting a preference for specific nucleotides at discrete positions flanking an internal cleavage site as well as during tRNA primer removal and plus-strand primer generation. RNA 5' end-directed and DNA 3' end-directed cleavages show similar sequence preferences at the positions closest to a cleavage site. A model for how RNase H selects cleavage sites is presented that incorporates both sequence preferences and the concept of a defined window for allowable cleavage from a recessed end. Finally, the RNase H activity of HIV-1 is considered as a target for anti-virals as well as a participant in drug resistance.
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Affiliation(s)
- Sharon J Schultz
- Department of Microbiology, School of Medicine, Box 357242, University of Washington, Seattle, WA 98195, USA
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14
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Priyakumar UD, Mackerell AD. Atomic detail investigation of the structure and dynamics of DNA.RNA hybrids: a molecular dynamics study. J Phys Chem B 2008; 112:1515-24. [PMID: 18197661 DOI: 10.1021/jp709827m] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
DNA.RNA hybrid duplexes are biologically important molecules and are shown to have potential therapeutic properties. To investigate the relationship between structures, energetics, solvation and RNase H activity of hybrid duplexes in comparison with pure DNA and RNA duplexes, a molecular dynamics study using the CHARMM27 force field was undertaken. The structural properties of all four nucleic acids considered are in very good agreement with the experimental data. The backbone dihedral angles and the puckering of the (deoxy)ribose indicate that the purine rich strands retain their A-/B-like properties but the pyrimidine rich DNA strand undergoes A-B conformational transitions. The minor groove widths of the hybrid structures are narrower than those in the RNA duplex, a requirement for RNase H binding. In addition, sampling of noncanonical phosphodiester backbone dihedrals by the DNA strands, differential solvation properties and helical properties, most notably rise, are suggested to contribute to hybrids being RNase H substrates. Differential RNase H activity toward hybrids containing purine versus pyrimidine rich RNA strands is suggested to be due to sampling of values of the phosphodiester backbone dihedrals in the DNA strands. Notably, the present results indicate that hybrids have decreased flexibility as compared to RNA, in contrast to previous reports.
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Affiliation(s)
- U Deva Priyakumar
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, Baltimore, Maryland 21201, USA
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15
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Pan B, Shi K, Sundaralingam M. Base-tetrad swapping results in dimerization of RNA quadruplexes: implications for formation of the i-motif RNA octaplex. Proc Natl Acad Sci U S A 2006; 103:3130-4. [PMID: 16492787 PMCID: PMC1413875 DOI: 10.1073/pnas.0507730103] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2005] [Indexed: 11/18/2022] Open
Abstract
Nucleic acids adopt different multistranded helical architectures to perform various biological functions. Here, we report a crystal structure of an RNA quadruplex containing "base-tetrad swapping" and bulged nucleotide at 2.1-Angstroms resolution. The base-tetrad swapping results in a dimer of quadruplexes with an intercalated octaplex fragment at the 5' end junction. The intercalated base tetrads provide the basic repeat unit for constructing a model of intercalated RNA octaplex. The model we obtained shows fundamentally different characteristics from duplex, triplex, and quadruplex. We also observed two different orientations of bulged uridine residues that are related to the interaction with surroundings. This structural evidence reflects the conformational flexibility of bulged nucleotides in RNA quadruplexes and implies the potential roles of bulged nucleotides as recognition and interaction sites in RNA-protein and RNA-RNA interactions.
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Affiliation(s)
- Baocheng Pan
- Departments of Chemistry and Biochemistry, Ohio State University, 200 Johnston Laboratory, 176 West 19th Avenue, Columbus, OH 43210-1002; and
| | - Ke Shi
- Department of Biochemistry, Molecular Biology, and Biophysics, University of Minnesota, 6-155 Jackson Hall, 321 Church Street Southeast, Minneapolis, MN 55455
| | - Muttaiya Sundaralingam
- Departments of Chemistry and Biochemistry, Ohio State University, 200 Johnston Laboratory, 176 West 19th Avenue, Columbus, OH 43210-1002; and
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Schultz SJ, Zhang M, Champoux JJ. Sequence, distance, and accessibility are determinants of 5'-end-directed cleavages by retroviral RNases H. J Biol Chem 2005; 281:1943-55. [PMID: 16306040 PMCID: PMC1360142 DOI: 10.1074/jbc.m510504200] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
The RNase H activity of reverse transcriptase is essential for retroviral replication. RNA 5'-end-directed cleavages represent a form of RNase H activity that is carried out on RNA/DNA hybrids that contain a recessed RNA 5'-end. Previously, the distance from the RNA 5'-end has been considered the primary determinant for the location of these cleavages. Employing model hybrid substrates and the HIV-1 and Moloney murine leukemia virus reverse transcriptases, we demonstrate that cleavage sites correlate with specific sequences and that the distance from the RNA 5'-end determines the extent of cleavage. An alignment of sequences flanking multiple RNA 5'-end-directed cleavage sites reveals that both enzymes strongly prefer A or U at the +1 position and C or G at the -2 position, and additionally for HIV-1, A is disfavored at the -4 position. For both enzymes, 5'-end-directed cleavages occurred when sites were positioned between the 13th and 20th nucleotides from the RNA 5'-end, a distance termed the cleavage window. In examining the importance of accessibility to the RNA 5'-end, it was found that the extent of 5'-end-directed cleavages observed in substrates containing a free recessed RNA 5'-end was most comparable to substrates with a gap of two or three bases between the upstream and downstream RNAs. Together these finding demonstrate that the selection of 5'-end-directed cleavage sites by retroviral RNases H results from a combination of nucleotide sequence, permissible distance, and accessibility to the RNA 5'-end.
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Affiliation(s)
- Sharon J Schultz
- Department of Microbiology, School of Medicine, University of Washington, Seattle, WA 98195, USA
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Abstract
Fifty years after the publication of the DNA double helix model by Watson and Crick, new nucleic acid structures keep emerging at an ever-increasing rate. The past three years have brought a flurry of new oligonucleotide structures, including those of a Hoogsteen-paired DNA duplex, Holliday junctions, DNA-drug complexes, quadruplexes, a host of RNA motifs and various nucleic acid analogues. Major advances were also made in terms of the structure and function of catalytic RNAs. These range from improved models of the phosphodiester cleavage reactions catalyzed by the hairpin and hepatitis delta virus ribozymes to the visualization of a complete active site of a group I self-splicing intron with bound 5'- and 3'-exons. These triumphs are complemented by a refined understanding of cation-nucleic-acid interactions and new routes to the generation of derivatives for phasing of DNA and RNA structures.
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Affiliation(s)
- Martin Egli
- Department of Biochemistry, Vanderbilt University, School of Medicine, Nashville, TN 37232, USA.
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18
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Schultz SJ, Zhang M, Champoux JJ. Recognition of internal cleavage sites by retroviral RNases H. J Mol Biol 2005; 344:635-52. [PMID: 15533434 DOI: 10.1016/j.jmb.2004.09.081] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2004] [Revised: 09/25/2004] [Accepted: 09/27/2004] [Indexed: 10/26/2022]
Abstract
The RNase H activity of reverse transcriptase is essential to complete retroviral replication. Many studies have characterized how reverse transcriptase associates with recessed and exposed DNA 3' ends or RNA 5' ends to position the RNase H domain for cleavage, but little is known about how a nick might affect RNase H cleavages, or how RNase H carries out internal cleavages, which do not require positioning by a nucleic acid end. We have addressed these issues using model hybrid substrates and the reverse transcriptases of Moloney murine leukemia virus (M-MuLV) and human immunodeficiency virus type 1 (HIV-1). Our results show that a nick separating an upstream RNA and a downstream RNA annealed to DNA is essentially ignored by RNase H, indicating that the RNA 5' end at a nick is not sufficient to position 5' end-directed cleavages. Cleavage sites that are located close to the 5' end of the downstream RNA are not recognized in the absence of the upstream RNA, and the 5' ends of the shorter upstream RNAs enhance cleavage at these sites. The recognition of an internal cleavage site depends on local sequence features found both upstream and downstream of the cleavage site, designated as the -1/+1 position. By analyzing the nucleotide frequencies in the sequence surrounding strong internal cleavage sites, preferred nucleotides have been identified in the flanking sequences spanning positions -14 to +1 for HIV-1 and -11 to +1 for M-MuLV. These data reveal that general degradation of the retroviral genome after minus-strand synthesis can occur through sequence-specific cleavages.
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Affiliation(s)
- Sharon J Schultz
- Department of Microbiology, Box 357242, School of Medicine, University of Washington, Seattle, WA 98195-7242, USA
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