Human mismatch repair protein MSH6 contains a PWWP domain that targets double stranded DNA.
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.
Laguri
Cédric
C
CEA Laboratoire de Biologie Structurale et Radiobiologie, iBiTec-Saclay, 91191 Gif sur Yvette, France.
Duband-Goulet
Isabelle
I
Friedrich
Nikolas
N
Axt
Marianne
M
Belin
Pascal
P
Callebaut
Isabelle
I
Gilquin
Bernard
B
Zinn-Justin
Sophie
S
Couprie
Joël
J
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
D004268:DNA-Binding Proteins; C094443:G-T mismatch-binding protein; D010446:Peptide Fragments; D004247:DNA