title: The solution structure of full-length dodecameric MCM by SANS and molecular modeling.
abstract: The solution structure of the full-length DNA helicase minichromosome maintenance protein from Methanothermobacter thermautotrophicus was determined by small-angle neutron scattering (SANS) data together with all-atom molecular modeling. The data were fit best with a dodecamer (dimer of hexamers). The 12 monomers were linked together by the B/C domains, and the adenosine triphosphatase (AAA+) catalytic regions were found to be freely movable in the full-length dodecamer both in the presence and absence of Mg(2+) and 50-meric single-stranded DNA (ssDNA). In particular, the SANS data and molecular modeling indicate that all 12 AAA+ domains in the dodecamer lie approximately the same distance from the axis of the molecule, but the positions of the helix-turn-helix region at the C-terminus of each monomer differ. In addition, the A domain at the N-terminus of each monomer is tucked up next to the AAA+ domain for all 12 monomers of the dodecamer. Finally, binding of ssDNA does not lock the AAA+ domains in any specific position, which leaves them with the flexibility to move both for helicase function and for binding along the ssDNA.
authors.affiliation: NIST Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland, 20899.
authors.forename: Susan
authors.initials: S
authors.lastname: Krueger
authors.forename: Jae-Ho
authors.initials: JH
authors.lastname: Shin
authors.forename: Joseph E
authors.initials: JE
authors.lastname: Curtis
authors.forename: Kenneth A
authors.initials: KA
authors.lastname: Rubinson
authors.forename: Zvi
authors.initials: Z
authors.lastname: Kelman
mesh_terms: D000595:Amino Acid Sequence; D019843:Archaeal Proteins / Q000737:chemistry*; D004265:DNA Helicases / Q000737:chemistry*; D004277:DNA, Single-Stranded / Q000737:chemistry; D017013:Methanobacteriaceae / Q000254:growth & development / Q000378:metabolism*; D008958:Models, Molecular; D056004:Molecular Dynamics Simulation; D008969:Molecular Sequence Data; D011487:Protein Conformation; D053838:Scattering, Small Angle; D012996:Solutions
chemical_list: D019843:Archaeal Proteins; D004277:DNA, Single-Stranded; D012996:Solutions; D004265:DNA Helicases; C403162:MCM protein, Methanobacterium thermoautotrophicum
keywords: DNA helicase; DNA replication; Monte Carlo simulations; minichromosome maintenance protein; small-angle neutron scattering