title: ATPase site architecture and helicase mechanism of an archaeal MCM.
abstract: The subunits of the presumptive replicative helicase of archaea and eukaryotes, the MCM complex, are members of the AAA+ (ATPase-associated with various cellular activities) family of ATPases. Proteins within this family harness the chemical energy of ATP hydrolysis to perform a broad range of cellular processes. Here, we investigate the function of the AAA+ site in the mini-chromosome maintenance (MCM) complex of the archaeon Sulfolobus solfataricus (SsoMCM). We find that SsoMCM has an unusual active-site architecture, with a unique blend of features previously found only in distinct families of AAA+ proteins. We additionally describe a series of mutant doping experiments to investigate the mechanistic basis of intersubunit coordination in the generation of helicase activity. Our results indicate that MCM can tolerate catalytically inactive subunits and still function as a helicase, leading us to propose a semisequential model for helicase activity of this complex.
authors.affiliation: MRC Cancer Cell Unit, Hutchison MRC Research Centre, Hills Road, Cambridge, CB2 2XZ, UK.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Moreau
authors.forename: Adam T
authors.initials: AT
authors.lastname: McGeoch
authors.forename: Alan R
authors.initials: AR
authors.lastname: Lowe
authors.forename: Laura S
authors.initials: LS
authors.lastname: Itzhaki
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Bell
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D019843:Archaeal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D003198:Computer Simulation; D004265:DNA Helicases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006868:Hydrolysis; D008666:Metalloendopeptidases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008956:Models, Chemical; D008958:Models, Molecular; D009010:Monte Carlo Method; D046912:Multiprotein Complexes / Q000737:chemistry; D016297:Mutagenesis, Site-Directed; D011487:Protein Conformation; D021122:Protein Subunits; D048229:Sulfolobus solfataricus / Q000201:enzymology* / Q000235:genetics
chemical_list: D019843:Archaeal Proteins; D046912:Multiprotein Complexes; D021122:Protein Subunits; D000255:Adenosine Triphosphate; D008666:Metalloendopeptidases; C114583:m-AAA proteases; D004265:DNA Helicases