Structural studies of MCM complex Minichromosome maintenance protein (MCM) complex functions as a helicase that unwinds DNA to provide template for DNA replication and plays a critical role in regulating cell growth. MCM helicases are considered to be a licensing factor for cellular DNA replication. MCM proteins from eukaryotes and archaea form hexamers ring complex, with MWt approximating 0.5-1.0 Mega Dolton. Despite extensive efforts, gap of knowledge exists in our understanding of how MCM unwinds DNA, how MCM interacts with DNA during unwinding, and how ATP is utilized to drive the conformational changes of MCM needed for unwinding. MCM are conserved in archaea and eukaryotes. Eukaryotic MCM contains six homologs that form hetero-hexamer and possibly higher order complexes. However, the MCM complex in some archaea contains only one MCM protein that can assemble into homo-hexamers or dodecamers. Thus, archaeal MCM homo-oligomers provide a simpler system for understanding the structure/function of MCM complex. The goal of this proposal is to use archaeal MCM complexes as a model system to understand the structure/functions of MCM complex, with particular emphasis on the mechanisms regarding oligomerization, ATP-triggered conformational changes, and DNA binding and remodeling functions of MCM proteins. A combination of structural biology, biophysics, and functional biochemistry will be employed for the study. The resulting data will provide valuable information for understanding the DNA unwinding mechanism at the replication fork. It will also provide structural/functional insights for the homologous eukaryotic MCM complex, which bears high relevance to cell growth regulation and cancer biology.

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Title: Structural studies of MCM complex One essential process for all living organisms is duplicate the genomic DNA (or DNA replication) to ensure correct genetic information passage. To duplicate genomic DNA, helicases is required to unzip the double helix DNA (dsDNA) to provide ssDNA template for daughter strand synthesis in the replication process. MCM complex is such a helicase that unwinds dsDNA and is critical for DNA replication and cell growth. We propose to study the structure/function of this important MCM helicase using a combination of approaches including structural biology, biophysics, and functional biochemistry, in order to understand how this enzyme utilizes the energy of ATP to unwind the double helix DNA for replication.

National Institute of Health (NIH)
National Institute of General Medical Sciences (NIGMS)
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Macromolecular Structure and Function C Study Section (MSFC)
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Preusch, Peter C
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University of Southern California
Schools of Arts and Sciences
Los Angeles
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Chang, Y Paul; Xu, Meng; Machado, Ana Carolina Dantas et al. (2013) Mechanism of origin DNA recognition and assembly of an initiator-helicase complex by SV40 large tumor antigen. Cell Rep 3:1117-27
Slaymaker, Ian M; Fu, Yang; Toso, Daniel B et al. (2013) Mini-chromosome maintenance complexes form a filament to remodel DNA structure and topology. Nucleic Acids Res 41:3446-56
Xu, Meng; Chang, Y Paul; Chen, Xiaojiang S (2013) Expression, purification and biochemical characterization of Schizosaccharomyces pombe Mcm4, 6 and 7. BMC Biochem 14:5
Brewster, Aaron S; Slaymaker, Ian M; Afif, Samir A et al. (2010) Mutational analysis of an archaeal minichromosome maintenance protein exterior hairpin reveals critical residues for helicase activity and DNA binding. BMC Mol Biol 11:62
Brewster, Aaron S; Chen, Xiaojiang S (2010) Insights into the MCM functional mechanism: lessons learned from the archaeal MCM complex. Crit Rev Biochem Mol Biol 45:243-56