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Minichromosome maintenance helicase activity is controlled by N- and C-terminal motifs and requires the ATPase domain of helix-2 insert

Jenkinson, E.J. and Chong, P.J. (2006) Minichromosome maintenance helicase activity is controlled by N- and C-terminal motifs and requires the ATPase domain of helix-2 insert. Proceedings of the National Academy of Sciences of the United States of America, 103 (20). pp. 7613-7618. ISSN 0027-8424

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Abstract

The minichromosome maintenance (MCM) proteins are essential conserved proteins required for DNA replication in archaea and eukaryotes. MCM proteins are believed to provide the replicative helicase activity that unwinds template DNA ahead of the replication fork. Consistent with this hypothesis, MCM proteins can form hexameric complexes that possess ATP-dependent DNA unwinding activity. The molecular mechanism by which the energy of ATP hydrolysis is harnessed to DNA unwinding is unknown, although the ATPase activity has been attributed to a highly conserved AAA+ family ATPase domain. Here we show that changes to N- and C-terminal motifs in the single MCM protein from the archaeon Methanothermobacter thermautotrophicus (MthMCM) can modulate ATP hydrolysis, DNA binding, and duplex unwinding. Furthermore, these motifs appear to influence the movement of the β-α-β insert in helix-2 of the MCM ATPase domain. Removal of this motif from MthMCM increased dsDNA-stimulated ATP hydrolysis and increased the affinity of the mutant complex for ssDNA and dsDNA. Deletion of the helix-2 insert additionally resulted in the abrogation of DNA unwinding. Our results provide significant insight into the molecular mechanisms used by the MCM helicase to both regulate and execute DNA unwinding.

Item Type: Article
Institution: The University of York
Academic Units: The University of York > Biology (York)
Depositing User: York RAE Import
Date Deposited: 20 Feb 2009 14:28
Last Modified: 20 Feb 2009 14:28
Published Version: http://dx.doi.org/10.1073/pnas.0509297103
Status: Published
Publisher: National Academy of Sciences
Identification Number: 10.1073/pnas.0509297103
URI: http://eprints.whiterose.ac.uk/id/eprint/7345

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