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Huang H, Weiner BE, Zhang H, Fuller BE, Gao Y, Wile BM, Zhao K, Arnett DR, Chazin WJ, Fanning E. Structure of a DNA polymerase alpha-primase domain that docks on the SV40 helicase and activates the viral primosome. J Biol Chem 2010; 285:17112-22. [PMID: 20234039 DOI: 10.1074/jbc.m110.116830] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
DNA polymerase alpha-primase (pol-prim) plays a central role in DNA replication in higher eukaryotes, initiating synthesis on both leading and lagging strand single-stranded DNA templates. Pol-prim consists of a primase heterodimer that synthesizes RNA primers, a DNA polymerase that extends them, and a fourth subunit, p68 (also termed B-subunit), that is thought to regulate the complex. Although significant knowledge about single-subunit primases of prokaryotes has accumulated, the functions and regulation of pol-prim remain poorly understood. In the SV40 replication model, the p68 subunit is required for primosome activity and binds directly to the hexameric viral helicase T antigen, suggesting a functional link between T antigen-p68 interaction and primosome activity. To explore this link, we first mapped the interacting regions of the two proteins and discovered a previously unrecognized N-terminal globular domain of p68 (p68N) that physically interacts with the T antigen helicase domain. NMR spectroscopy was used to determine the solution structure of p68N and map its interface with the T antigen helicase domain. Structure-guided mutagenesis of p68 residues in the interface diminished T antigen-p68 interaction, confirming the interaction site. SV40 primosome activity of corresponding pol-prim mutants decreased in proportion to the reduction in p68N-T antigen affinity, confirming that p68-T antigen interaction is vital for primosome function. A model is presented for how this interaction regulates SV40 primosome activity, and the implications of our findings are discussed in regard to the molecular mechanisms of eukaryotic DNA replication initiation.
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Affiliation(s)
- Hao Huang
- Department of Biological Sciences, Vanderbilt University, Nashville, Tennessee 37232, USA
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155
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Thangavel S, Mendoza-Maldonado R, Tissino E, Sidorova JM, Yin J, Wang W, Monnat RJ, Falaschi A, Vindigni A. Human RECQ1 and RECQ4 helicases play distinct roles in DNA replication initiation. Mol Cell Biol 2010; 30:1382-96. [PMID: 20065033 PMCID: PMC2832491 DOI: 10.1128/mcb.01290-09] [Citation(s) in RCA: 115] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2009] [Revised: 10/26/2009] [Accepted: 12/29/2009] [Indexed: 11/20/2022] Open
Abstract
Cellular and biochemical studies support a role for all five human RecQ helicases in DNA replication; however, their specific functions during this process are unclear. Here we investigate the in vivo association of the five human RecQ helicases with three well-characterized human replication origins. We show that only RECQ1 (also called RECQL or RECQL1) and RECQ4 (also called RECQL4) associate with replication origins in a cell cycle-regulated fashion in unperturbed cells. RECQ4 is recruited to origins at late G(1), after ORC and MCM complex assembly, while RECQ1 and additional RECQ4 are loaded at origins at the onset of S phase, when licensed origins begin firing. Both proteins are lost from origins after DNA replication initiation, indicating either disassembly or tracking with the newly formed replisome. Nascent-origin DNA synthesis and the frequency of origin firing are reduced after RECQ1 depletion and, to a greater extent, after RECQ4 depletion. Depletion of RECQ1, though not that of RECQ4, also suppresses replication fork rates in otherwise unperturbed cells. These results indicate that RECQ1 and RECQ4 are integral components of the human replication complex and play distinct roles in DNA replication initiation and replication fork progression in vivo.
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Affiliation(s)
- Saravanabhavan Thangavel
- International Centre for Genetic Engineering and Biotechnology, Padriciano 99, 34149 Trieste, Italy, Laboratorio di Biologia Molecolare, Scuola Normale Superiore, Via Moruzzi 1, Pisa I-56124, Italy, Departments of Pathology, Genome Sciences, University of Washington, Seattle, Washington 98195-7705, Laboratory of Genetics, National Institute on Aging, National Institutes of Health, NIH Biomedical Research Center, Baltimore, Maryland 21224, Istituto di Fisiologia Clinica, CNR, Via Moruzzi 1, I-56124 Pisa, Italy
| | - Ramiro Mendoza-Maldonado
- International Centre for Genetic Engineering and Biotechnology, Padriciano 99, 34149 Trieste, Italy, Laboratorio di Biologia Molecolare, Scuola Normale Superiore, Via Moruzzi 1, Pisa I-56124, Italy, Departments of Pathology, Genome Sciences, University of Washington, Seattle, Washington 98195-7705, Laboratory of Genetics, National Institute on Aging, National Institutes of Health, NIH Biomedical Research Center, Baltimore, Maryland 21224, Istituto di Fisiologia Clinica, CNR, Via Moruzzi 1, I-56124 Pisa, Italy
| | - Erika Tissino
- International Centre for Genetic Engineering and Biotechnology, Padriciano 99, 34149 Trieste, Italy, Laboratorio di Biologia Molecolare, Scuola Normale Superiore, Via Moruzzi 1, Pisa I-56124, Italy, Departments of Pathology, Genome Sciences, University of Washington, Seattle, Washington 98195-7705, Laboratory of Genetics, National Institute on Aging, National Institutes of Health, NIH Biomedical Research Center, Baltimore, Maryland 21224, Istituto di Fisiologia Clinica, CNR, Via Moruzzi 1, I-56124 Pisa, Italy
| | - Julia M. Sidorova
- International Centre for Genetic Engineering and Biotechnology, Padriciano 99, 34149 Trieste, Italy, Laboratorio di Biologia Molecolare, Scuola Normale Superiore, Via Moruzzi 1, Pisa I-56124, Italy, Departments of Pathology, Genome Sciences, University of Washington, Seattle, Washington 98195-7705, Laboratory of Genetics, National Institute on Aging, National Institutes of Health, NIH Biomedical Research Center, Baltimore, Maryland 21224, Istituto di Fisiologia Clinica, CNR, Via Moruzzi 1, I-56124 Pisa, Italy
| | - Jinhu Yin
- International Centre for Genetic Engineering and Biotechnology, Padriciano 99, 34149 Trieste, Italy, Laboratorio di Biologia Molecolare, Scuola Normale Superiore, Via Moruzzi 1, Pisa I-56124, Italy, Departments of Pathology, Genome Sciences, University of Washington, Seattle, Washington 98195-7705, Laboratory of Genetics, National Institute on Aging, National Institutes of Health, NIH Biomedical Research Center, Baltimore, Maryland 21224, Istituto di Fisiologia Clinica, CNR, Via Moruzzi 1, I-56124 Pisa, Italy
| | - Weidong Wang
- International Centre for Genetic Engineering and Biotechnology, Padriciano 99, 34149 Trieste, Italy, Laboratorio di Biologia Molecolare, Scuola Normale Superiore, Via Moruzzi 1, Pisa I-56124, Italy, Departments of Pathology, Genome Sciences, University of Washington, Seattle, Washington 98195-7705, Laboratory of Genetics, National Institute on Aging, National Institutes of Health, NIH Biomedical Research Center, Baltimore, Maryland 21224, Istituto di Fisiologia Clinica, CNR, Via Moruzzi 1, I-56124 Pisa, Italy
| | - Raymond J. Monnat
- International Centre for Genetic Engineering and Biotechnology, Padriciano 99, 34149 Trieste, Italy, Laboratorio di Biologia Molecolare, Scuola Normale Superiore, Via Moruzzi 1, Pisa I-56124, Italy, Departments of Pathology, Genome Sciences, University of Washington, Seattle, Washington 98195-7705, Laboratory of Genetics, National Institute on Aging, National Institutes of Health, NIH Biomedical Research Center, Baltimore, Maryland 21224, Istituto di Fisiologia Clinica, CNR, Via Moruzzi 1, I-56124 Pisa, Italy
| | - Arturo Falaschi
- International Centre for Genetic Engineering and Biotechnology, Padriciano 99, 34149 Trieste, Italy, Laboratorio di Biologia Molecolare, Scuola Normale Superiore, Via Moruzzi 1, Pisa I-56124, Italy, Departments of Pathology, Genome Sciences, University of Washington, Seattle, Washington 98195-7705, Laboratory of Genetics, National Institute on Aging, National Institutes of Health, NIH Biomedical Research Center, Baltimore, Maryland 21224, Istituto di Fisiologia Clinica, CNR, Via Moruzzi 1, I-56124 Pisa, Italy
| | - Alessandro Vindigni
- International Centre for Genetic Engineering and Biotechnology, Padriciano 99, 34149 Trieste, Italy, Laboratorio di Biologia Molecolare, Scuola Normale Superiore, Via Moruzzi 1, Pisa I-56124, Italy, Departments of Pathology, Genome Sciences, University of Washington, Seattle, Washington 98195-7705, Laboratory of Genetics, National Institute on Aging, National Institutes of Health, NIH Biomedical Research Center, Baltimore, Maryland 21224, Istituto di Fisiologia Clinica, CNR, Via Moruzzi 1, I-56124 Pisa, Italy
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