Display Settings:

Format

Send to:

Choose Destination
See comment in PubMed Commons below
J Biol Chem. 2007 Nov 16;282(46):33795-804. Epub 2007 Sep 25.

Differences in the single-stranded DNA binding activities of MCM2-7 and MCM467: MCM2 and MCM5 define a slow ATP-dependent step.

Author information

  • 1Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.

Abstract

The MCM2-7 complex, a hexamer containing six distinct and essential subunits, is postulated to be the eukaryotic replicative DNA helicase. Although all six subunits function at the replication fork, only a specific subcomplex consisting of the MCM4, 6, and 7 subunits (MCM467) and not the MCM2-7 complex exhibits DNA helicase activity in vitro. To understand why MCM2-7 lacks helicase activity and to address the possible function of the MCM2, 3, and 5 subunits, we have compared the biochemical properties of the Saccharomyces cerevisiae MCM2-7 and MCM467 complexes. We demonstrate that both complexes are toroidal and possess a similar ATP-dependent single-stranded DNA (ssDNA) binding activity, indicating that the lack of helicase activity by MCM2-7 is not due to ineffective ssDNA binding. We identify two important differences between them. MCM467 binds dsDNA better than MCM2-7. In addition, we find that the rate of MCM2-7/ssDNA association is slow compared with MCM467; the association rate can be dramatically increased either by preincubation with ATP or by inclusion of mutations that ablate the MCM2/5 active site. We propose that the DNA binding differences between MCM2-7 and MCM467 correspond to a conformational change at the MCM2/5 active site with putative regulatory significance.

PMID:
17895243
[PubMed - indexed for MEDLINE]
Free full text
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Full text links

    Icon for HighWire
    Loading ...
    Write to the Help Desk