title: The MutSalpha-proliferating cell nuclear antigen interaction in human DNA mismatch repair.
abstract: We have examined the interaction parameters, conformation, and functional significance of the human MutSalpha(.) proliferating cell nuclear antigen (PCNA) complex in mismatch repair. The two proteins associate with a 1:1 stoichiometry and a K(D) of 0.7 microm in the absence or presence of heteroduplex DNA. PCNA does not influence the affinity of MutSalpha for a mismatch, and mismatch-bound MutSalpha binds PCNA. Small angle x-ray scattering studies have established the molecular parameters of the complex, which are consistent with an elongated conformation in which the two proteins associate in an end-to-end fashion in a manner that does not involve an extended unstructured tether, as has been proposed for yeast MutSalpha and PCNA ( Shell, S. S., Putnam, C. D., and Kolodner, R. D. (2007) Mol. Cell 26, 565-578 ). MutSalpha variants lacking the PCNA interaction motif are functional in 3'- or 5'-directed mismatch-provoked excision, but display a partial defect in 5'-directed mismatch repair. This finding is consistent with the modest mutability conferred by inactivation of the MutSalpha PCNA interaction motif and suggests that interaction of the replication clamp with other repair protein(s) accounts for the essential role of PCNA in MutSalpha-dependent mismatch repair.
authors.affiliation: Department of Biochemistry, Duke University Medical Center, Durham, North Carolina 27710, USA.
authors.forename: Ravi R
authors.initials: RR
authors.lastname: Iyer
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Pohlhaus
authors.forename: Sihong
authors.initials: S
authors.lastname: Chen
authors.forename: Gregory L
authors.initials: GL
authors.lastname: Hura
authors.forename: Leonid
authors.initials: L
authors.lastname: Dzantiev
authors.forename: Lorena S
authors.initials: LS
authors.lastname: Beese
authors.forename: Paul
authors.initials: P
authors.lastname: Modrich
mesh_terms: D000595:Amino Acid Sequence; D055592:Biophysical Phenomena; D001703:Biophysics; D053843:DNA Mismatch Repair; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019281:Dimerization; D006367:HeLa Cells; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D051718:MutS Homolog 2 Protein / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018809:Proliferating Cell Nuclear Antigen / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary
chemical_list: D004268:DNA-Binding Proteins; C094443:G-T mismatch-binding protein; D018809:Proliferating Cell Nuclear Antigen; C497172:MSH2 protein, human; D051718:MutS Homolog 2 Protein