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Structural studies of the archaeal MCM complex in different functional states
被引:45
作者:
Costa, Alessandro
Pape, Tillmann
van Heel, Marin
Brick, Peter
Patwardhan, Ardan
[1
]
Onesti, Silvia
机构:
[1] Imperial Coll, Div Cell & Mol Biol, London SW7 2AZ, England
[2] Imperial Coll, Div Mol Biosci, London SW7 2AZ, England
基金:
英国惠康基金;
英国生物技术与生命科学研究理事会;
关键词:
AAA plus proteins;
MCM;
helicase;
DNA replication;
symmetry analysis;
D O I:
10.1016/j.jsb.2006.04.001
中图分类号:
Q5 [生物化学];
Q7 [分子生物学];
学科分类号:
071010 ;
081704 ;
摘要:
The primary candidate for the eukaryotic replicative helicase is the MCM2-7 complex, a hetero-oligomer formed by six AAA+ paralogous polypeptides. A simplified model for structure-function studies is the homo-oligomeric orthologue from the archaeon Methanothermobacter thermoautotrophicus. The crystal structure of the DNA-interacting N-terminal domain of this homo-oligomer revealed a double hexamer in a head-to-head configuration; single-particle electron microscopy studies have shown that the full-length protein complex can form both single and double rings, in which each ring can consist of a cyclical arrangement of six or seven subunits. Using single-particle techniques and especially multivariate statistical symmetry analysis, we have assessed the changes in stoichiometry that the complex undergoes when treated with various nucleotide analogues or when binding a double-stranded DNA fragment. We found that the binding of nucleotides or of double-stranded DNA leads to the preferred formation of double-ring structures. Specifically, the protein complex is present as a double heptamer when treated with a nucleotide analogue, but it is rather found as a double hexamer when complexed with double-stranded DNA. The possible physiological role of the various stoichiometries of the complex is discussed in the light of the proposed mechanisms of helicase activity. (c) 2006 Elsevier Inc. All rights reserved.
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页码:210 / 219
页数:10
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