title: Molecular architecture of a multifunctional MCM complex.
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 ATPγS 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.
authors: Structural Biology and Biocomputing Programme, Macromolecular Crystallography Group, Spanish National Cancer Research Center (CNIO), c/Melchor Fdez. Almagro 3, 28029-Madrid, Spain.
authors: June
authors: J
authors: Sanchez-Berrondo
authors: Pablo
authors: P
authors: Mesa
authors: Arkaitz
authors: A
authors: Ibarra
authors: Maria I
authors: MI
authors: Martínez-Jiménez
authors: Luis
authors: L
authors: Blanco
authors: Juan
authors: J
authors: Méndez
authors: Jasminka
authors: J
authors: Boskovic
authors: Guillermo
authors: G
authors: Montoya
mesh_terms: D000244:Adenosine Diphosphate / Q000737:chemistry; D000251:Adenosine Triphosphatases / Q000737:chemistry / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism; D001409:Bacillus cereus / Q000201:enzymology; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D004247:DNA / Q000378:metabolism; D004265:DNA Helicases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D019915:DNA Primase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism / Q000648:ultrastructure; D004277:DNA, Single-Stranded / Q000737:chemistry / Q000378:metabolism; D004259:DNA-Directed DNA Polymerase / Q000378:metabolism; D003854:Deoxyribonucleotides / Q000378:metabolism; D008958:Models, Molecular; D009154:Mutation; D017434:Protein Structure, Tertiary
chemical_list: D001426:Bacterial Proteins; D004277:DNA, Single-Stranded; D003854:Deoxyribonucleotides; C022571:adenosine 5'-O-(3-thiotriphosphate); D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D004247:DNA; D019915:DNA Primase; D004259:DNA-Directed DNA Polymerase; D000251:Adenosine Triphosphatases; D004265:DNA Helicases