title: Human mismatch repair protein MSH6 contains a PWWP domain that targets double stranded DNA.
abstract: The eukaryotic mismatch repair (MMR) protein MSH6 exhibits a core region structurally and functionally similar to bacterial MutS. However, it possesses an additional N-terminal region (NTR), comprising a PCNA binding motif, a large region of unknown function and a nonspecific DNA binding fragment. Yeast NTR was recently described as an extended tether between PCNA and the core of MSH6 . In contrast, we show that human NTR presents a globular PWWP domain in the region of unknown function. We demonstrate that this PWWP domain binds double-stranded DNA, without any preference for mismatches or nicks, whereas its apparent affinity for single-stranded DNA is about 20 times lower. The S144I mutation, which in human MSH6 causes inherited somatic defects in MMR resulting in increased development of hereditary non polyposis colorectal cancer , is located in the DNA binding surface of the PWWP domain. However, it only moderately affects domain stability, and it does not perturb DNA binding in vitro.
authors.affiliation: CEA Laboratoire de Biologie Structurale et Radiobiologie, iBiTec-Saclay, 91191 Gif sur Yvette, France.
authors.forename: Cédric
authors.initials: C
authors.lastname: Laguri
authors.forename: Isabelle
authors.initials: I
authors.lastname: Duband-Goulet
authors.forename: Nikolas
authors.initials: N
authors.lastname: Friedrich
authors.forename: Marianne
authors.initials: M
authors.lastname: Axt
authors.forename: Pascal
authors.initials: P
authors.lastname: Belin
authors.forename: Isabelle
authors.initials: I
authors.lastname: Callebaut
authors.forename: Bernard
authors.initials: B
authors.lastname: Gilquin
authors.forename: Sophie
authors.initials: S
authors.lastname: Zinn-Justin
authors.forename: Joël
authors.initials: J
authors.lastname: Couprie
mesh_terms: D000595:Amino Acid Sequence; D020137:Base Pair Mismatch; D001665:Binding Sites; D002850:Chromatography, Gel; D015179:Colorectal Neoplasms / Q000235:genetics; D017124:Conserved Sequence; D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics*; D006801:Humans; D007700:Kinetics; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000302:isolation & purification; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D004268:DNA-Binding Proteins; C094443:G-T mismatch-binding protein; D010446:Peptide Fragments; D004247:DNA