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Molecular architecture of a multifunctional MCM complex (2011)
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BibTeX
@MISC{Sanchez-berrondo11moleculararchitecture,
author = {June Sanchez-berrondo and Pablo Mesa and Arkaitz Ibarra and Maria I. Martínez-jiménez and Luis Blanco and Juan Méndez and Jasminka Boskovic and Guillermo Montoya},
title = {Molecular architecture of a multifunctional MCM complex},
year = {2011}
}
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Abstract
DNA replication is strictly regulated through a sequence of steps that involve many macromolecular protein complexes. One of them is the replicative helicase, which is required for initiation and elongation phases. A MCM helicase found as a prophage in the genome of Bacillus cereus is fused with a primase domain constituting an integrative arrangement of two essential activities for replication. We have isolated this helicase–primase complex (BcMCM) showing that it can bind DNA and displays not only helicase and primase but also DNA polymerase activity. Using single-particle electron microscopy and 3D reconstruction, we obtained structures of BcMCM using ATPcS or ADP in the absence and presence of DNA. The complex depicts the typical hexameric ring shape. The dissection of the unwinding mechanism using site-directed mutagenesis in the Walker A, Walker B, arginine finger and the helicase channels, suggests that the BcMCM complex unwinds DNA following the extrusion model similarly to the E1 helicase from papillomavirus.
Keyphrases
molecular architecture multifunctional mcm complex typical hexameric ring shape essential activity extrusion model arginine finger helicase channel dna polymerase activity many macromolecular protein complex primase domain mcm helicase e1 helicase integrative arrangement bcmcm complex unwinds dna single-particle electron microscopy bacillus cereus site-directed mutagenesis helicase primase complex dna replication unwinding mechanism replicative helicase elongation phase
