HNPCC mutations in hMSH2 result in reduced hMSH2-hMSH6 molecular switch functions.
Mutations in the human mismatch repair (MMR) gene hMSH2 have been linked to approximately 40% of hereditary nonpolyposis colorectal cancers (HNPCC). While the consequences of deletion or truncating mutations of hMSH2 would appear clear, the detailed functional defects associated with missense alterations are unknown. We have examined the effect of seven single amino acid substitutions associated with HNPCC that cover the structural subdomains of the hMSH2 protein. We show that alterations which produced a known cancer-causing phenotype affected the mismatch-dependent molecular switch function of the biologically relevant hMSH2-hMSH6 heterodimer. Our observations demonstrate that amino acid substitutions within hMSH2 that are distant from known functional regions significantly alter biochemical activity and the ability of hMSH2-hMSH6 to form a sliding clamp.
Genetics and Molecular Biology Program, Department of Microbiology and Immunology, Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
Christopher D
CD
Heinen
Teresa
T
Wilson
Anthony
A
Mazurek
Mark
M
Berardini
Charles
C
Butz
Richard
R
Fishel
D000244:Adenosine Diphosphate / Q000378:metabolism; D000251:Adenosine Triphosphatases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D020137:Base Pair Mismatch / Q000235:genetics; D001665:Binding Sites / Q000235:genetics; D003123:Colorectal Neoplasms, Hereditary Nonpolyposis / Q000235:genetics*; D004247:DNA / Q000378:metabolism; D004260:DNA Repair / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics*; D019281:Dimerization; D024202:Electrophoretic Mobility Shift Assay; D006801:Humans; D006868:Hydrolysis; D051718:MutS Homolog 2 Protein; D016296:Mutagenesis / Q000235:genetics; D020125:Mutation, Missense / Q000235:genetics; D011485:Protein Binding / Q000235:genetics; D011518:Proto-Oncogene Proteins / Q000235:genetics*
D004268:DNA-Binding Proteins; C094443:G-T mismatch-binding protein; D011518:Proto-Oncogene Proteins; D000244:Adenosine Diphosphate; D000255:Adenosine Triphosphate; D004247:DNA; D000251:Adenosine Triphosphatases; C497172:MSH2 protein, human; D051718:MutS Homolog 2 Protein