title: Hereditary cancer-associated missense mutations in hMSH6 uncouple ATP hydrolysis from DNA mismatch binding.
abstract: Hereditary nonpolyposis colorectal cancer is caused by germline mutations in DNA mismatch repair genes. The majority of cases are associated with mutations in hMSH2 or hMLH1; however, about 12% of cases are associated with alterations in hMSH6. The hMSH6 protein forms a heterodimer with hMSH2 that is capable of recognizing a DNA mismatch. The heterodimer then utilizes its adenosine nucleotide processing ability in an, as of yet, unclear mechanism to facilitate communication between the mismatch and a distant strand discrimination site. The majority of reported mutations in hMSH6 are deletions or truncations that entirely eliminate the function of the protein; however, nearly a third of the reported variations are missense mutations whose functional significance is unclear. We analyzed seven cancer-associated single amino acid alterations in hMSH6 distributed throughout the functional domains of the protein to determine their effect on the biochemical activity of the hMSH2-hMSH6 heterodimer. Five alterations affect mismatch-stimulated ATP hydrolysis activity providing functional evidence that missense variants of hMSH6 can disrupt mismatch repair function and may contribute to disease. Of the five mutants that affect mismatch-stimulated ATP hydrolysis, only two (R976H and H1248D) affect mismatch recognition. Thus, three of the mutants (G566R, V878A, and D803G) appear to uncouple the mismatch binding and ATP hydrolysis activities of the heterodimer. We also demonstrate that these three mutations alter ATP-dependent conformation changes of hMSH2-hMSH6, suggesting that cancer-associated mutations in hMSH6 can disrupt the intramolecular signaling that coordinates mismatch binding with adenosine nucleotide processing.
authors.affiliation: Neag Comprehensive Cancer Center, University of Connecticut Health Center, Farmington, Connecticut 06030, USA.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Cyr
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Heinen
mesh_terms: D000244:Adenosine Diphosphate / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism*; D020137:Base Pair Mismatch / Q000235:genetics*; D003123:Colorectal Neoplasms, Hereditary Nonpolyposis / Q000201:enzymology* / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D006868:Hydrolysis; D008958:Models, Molecular; D051718:MutS Homolog 2 Protein / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020125:Mutation, Missense / Q000235:genetics*; D011485:Protein Binding; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary
chemical_list: D004268:DNA-Binding Proteins; C094443:G-T mismatch-binding protein; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D000251:Adenosine Triphosphatases; C497172:MSH2 protein, human; D051718:MutS Homolog 2 Protein
references.citation: J Biol Chem. 2004 Jul 2;279(27):28402-10
references.pmid: 15105434
references.citation: J Biol Chem. 2005 Jun 10;280(23):22245-57
references.pmid: 15811858
references.citation: J Am Soc Mass Spectrom. 1994 Nov;5(11):976-89
references.pmid: 24226387
references.citation: Dis Colon Rectum. 1991 May;34(5):424-5
references.pmid: 2022152
references.citation: Cancer Res. 2002 May 1;62(9):2447-54
references.pmid: 11980631
references.citation: Gastroenterology. 2004 Jul;127(1):17-25
references.pmid: 15236168
references.citation: Proc Natl Acad Sci U S A. 2006 Jan 17;103(3):558-63
references.pmid: 16407100
references.citation: Mol Cell. 2006 Apr 7;22(1):39-49
references.pmid: 16600868
references.citation: Cell. 2006 Nov 3;127(3):635-48
references.pmid: 17081983
references.citation: EMBO J. 1997 Jul 16;16(14):4467-76
references.pmid: 9250691
references.citation: Nat Rev Mol Cell Biol. 2006 May;7(5):335-46
references.pmid: 16612326
references.citation: Genes Dev. 1998 Jul 15;12(14):2096-101
references.pmid: 9679053
references.citation: Am J Hum Genet. 2002 Jan;70(1):26-37
references.pmid: 11709755
references.citation: Nat Genet. 1999 Oct;23(2):142-4
references.pmid: 10508506
references.citation: Hum Mol Genet. 2002 May 15;11(11):1303-10
references.pmid: 12019211
references.citation: Fam Cancer. 2005;4(4):323-33
references.pmid: 16341812
references.citation: Biochemistry. 2008 Jun 10;47(23):6199-207
references.pmid: 18484749
references.citation: Biochemistry. 2003 Jul 1;42(25):7682-93
references.pmid: 12820877
references.citation: Mol Cell. 2001 Jan;7(1):1-12
references.pmid: 11172706
references.citation: Mol Cell Proteomics. 2005 Feb;4(2):169-81
references.pmid: 15598749
references.citation: Am J Hum Genet. 1999 Nov;65(5):1291-8
references.pmid: 10521294
references.citation: Curr Biol. 1999 Aug 26;9(16):907-10
references.pmid: 10469597
references.citation: Mol Cell. 2007 May 25;26(4):579-92
references.pmid: 17531815
references.citation: J Biol Chem. 1998 Nov 27;273(48):32049-54
references.pmid: 9822679
references.citation: Cancer. 2007 Jun 1;109(11):2349-56
references.pmid: 17440981
references.citation: Hum Mutat. 2007 Jul;28(7):669-73
references.pmid: 17347989
references.citation: J Biol Chem. 2001 Sep 7;276(36):34339-47
references.pmid: 11454861
references.citation: Cell Res. 2008 Jan;18(1):85-98
references.pmid: 18157157
references.citation: Cancer Genet Cytogenet. 1997 Jan;93(1):84-99
references.pmid: 9062584
references.citation: Cell. 1997 Dec 26;91(7):995-1005
references.pmid: 9428522
references.citation: Cancer Res. 1999 Oct 15;59(20):5068-74
references.pmid: 10537275
references.citation: Mol Cell Biol. 1997 May;17(5):2436-47
references.pmid: 9111312
references.citation: Mol Cell. 1999 Feb;3(2):255-61
references.pmid: 10078208
references.citation: Int J Cancer. 2002 Feb 10;97(5):643-8
references.pmid: 11807791
references.citation: Mol Cell Biol. 1998 Nov;18(11):6616-23
references.pmid: 9774676
references.citation: Cancer Cell. 2002 Jun;1(5):469-78
references.pmid: 12124176
references.citation: Hum Mutat. 2007 Nov;28(11):1047-54
references.pmid: 17594722
references.citation: EMBO J. 1991 Sep;10(9):2707-15
references.pmid: 1651234