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Ruhel R, Mazumder M, Gnanasekaran P, Kumar M, Gourinath S, Chakraborty S. Functional implications of residues of the B' motif of geminivirus replication initiator protein in its helicase activity. FEBS J 2021; 288:6492-6509. [PMID: 34092039 DOI: 10.1111/febs.16053] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2020] [Revised: 04/15/2021] [Accepted: 06/04/2021] [Indexed: 01/03/2023]
Abstract
Geminivirus replication initiator protein (Rep) is a multifunctional viral protein required for replication. During the process of viral replication, Rep acts as a site- and strand-specific endonuclease, ligase, ATPase, and helicase. B' motif and β-hairpin loop of the geminivirus Rep are conserved and important for Rep-mediated helicase activity required for viral replication. To dissect the roles of various amino acid residues of the B' motif and β-hairpin loop of the geminivirus Rep helicase in its process of unwinding DNA, we investigated eight conserved residues near the ATP active site or the ssDNA contact channel. Our strategy was to mutate these residues to alanines and investigate the effects of these mutations on various biochemical activities associated with DNA unwinding. We looked into the ATP binding, ATP hydrolysis, DNA binding, and DNA unwinding activities of the wild-type and mutant Rep proteins. These investigations showed four residues (Arg279, Asp280, Tyr287, and Pro290) affecting the DNA unwinding activity. A structural model analysis confirmed the B' loop and ssDNA binding loop to be connected through a β-hairpin structure, suggesting that changes on one loop might affect the other and that these residues function by acting in concert. Viral genomes containing Rep proteins having these mutations in the B' motif did not replicate in planta. Taken together, these results indicated all four residues to be implicated in helicase activity mediated by Rep and demonstrated the significance, for viral replication, of the B' motif and β-hairpin loop of the C-terminal region of the Rep protein.
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Affiliation(s)
- Rajrani Ruhel
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Mohit Mazumder
- Structural Biology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Prabu Gnanasekaran
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Manish Kumar
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Samudrala Gourinath
- Structural Biology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
| | - Supriya Chakraborty
- Molecular Virology Laboratory, School of Life Sciences, Jawaharlal Nehru University, New Delhi, India
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Wu M, Wei H, Tan H, Pan S, Liu Q, Bejarano ER, Lozano-Durán R. Plant DNA polymerases α and δ mediate replication of geminiviruses. Nat Commun 2021; 12:2780. [PMID: 33986276 PMCID: PMC8119979 DOI: 10.1038/s41467-021-23013-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 04/06/2021] [Indexed: 12/19/2022] Open
Abstract
Geminiviruses are causal agents of devastating diseases in crops. Geminiviruses have circular single-stranded (ss) DNA genomes that are replicated in the nucleus of the infected plant cell through double-stranded (ds) DNA intermediates by the plant DNA replication machinery. Which host DNA polymerase mediates geminiviral multiplication, however, has so far remained elusive. Here, we show that subunits of the nuclear replicative DNA polymerases α and δ physically interact with the geminivirus-encoded replication enhancer protein, C3, and that these polymerases are required for viral replication. Our results suggest that, while DNA polymerase α is essential to generate the viral dsDNA intermediate, DNA polymerase δ mediates the synthesis of new copies of the geminiviral ssDNA genome, and that the virus-encoded C3 may act selectively, recruiting DNA polymerase δ over ε to favour productive replication.
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Affiliation(s)
- Mengshi Wu
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, China
- Bioinformatics Department, School of Life Sciences and Technology, Tongji University, Shanghai, China
- University of the Chinese Academy of Sciences, Beijing, China
| | - Hua Wei
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, China
- University of the Chinese Academy of Sciences, Beijing, China
| | - Huang Tan
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, China
- University of the Chinese Academy of Sciences, Beijing, China
| | - Shaojun Pan
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, China
- University of the Chinese Academy of Sciences, Beijing, China
| | - Qi Liu
- Bioinformatics Department, School of Life Sciences and Technology, Tongji University, Shanghai, China
| | - Eduardo R Bejarano
- Instituto de Hortofruticultura Subtropical y Mediterránea "La Mayora" (IHSM-UMA-CSIC), Area de Genética, Facultad de Ciencias, Universidad de Málaga, Campus de Teatinos s/n, Málaga, Spain
| | - Rosa Lozano-Durán
- Shanghai Center for Plant Stress Biology, CAS Center for Excellence in Molecular Plant Sciences, Chinese Academy of Sciences, Shanghai, China.
- Department of Plant Biochemistry, Centre for Plant Molecular Biology (ZMBP), Eberhard Karls University, Tübingen, Germany.
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