title: Structural analysis of the Sulfolobus solfataricus MCM protein N-terminal domain.
abstract: The Mini-Chromosome Maintenance (MCM) proteins are candidates of replicative DNA helicase in eukarya and archaea. Here we report a 2.8 A crystal structure of the N-terminal domain (residues 1-268) of the Sulfolobus solfataricus MCM (Sso MCM) protein. The structure reveals single-hexameric ring-like architecture, at variance from the protein of Methanothermobacter thermoautotrophicus (Mth). Moreover, the central channel in Sso MCM seems significantly narrower than the Mth counterpart, which appears to more favorably accommodate single-stranded DNA than double-stranded DNA, as supported by DNA-binding assays. Structural analysis also highlights the essential role played by the zinc-binding domain in the interaction with nucleic acids and allows us to speculate that the Sso MCM N-ter domain may function as a molecular clamp to grasp the single-stranded DNA passing through the central channel. On this basis possible DNA unwinding mechanisms are discussed.
authors.affiliation: Center of Structural Biochemistry, Karolinska Institutet NOVUM, 141 57 Huddinge, Sweden. wei.liu@ki.se
authors.forename: Wei
authors.initials: W
authors.lastname: Liu
authors.forename: Biagio
authors.initials: B
authors.lastname: Pucci
authors.forename: Mosè
authors.initials: M
authors.lastname: Rossi
authors.forename: Francesca M
authors.initials: FM
authors.lastname: Pisani
authors.forename: Rudolf
authors.initials: R
authors.lastname: Ladenstein
mesh_terms: D000595:Amino Acid Sequence; D019843:Archaeal Proteins / Q000737:chemistry; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D001665:Binding Sites; D018360:Crystallography, X-Ray; D004265:DNA Helicases / Q000737:chemistry* / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism; D017013:Methanobacteriaceae / Q000201:enzymology; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000737:chemistry; D017384:Sequence Deletion; D040681:Structural Homology, Protein; D048229:Sulfolobus solfataricus / Q000201:enzymology*; D015032:Zinc / Q000737:chemistry
chemical_list: D019843:Archaeal Proteins; D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D021122:Protein Subunits; D004265:DNA Helicases; D015032:Zinc