MAPPING THE MINIMAL DOMAIN OF HMSH-2 SUFFICIENT FOR BINDING MISMATCHED OLIGONUCLEOTIDES

The human MSH-2 gene product is a member of a highly conserved family of proteins involved in postreplication mismatch repair. Germline muta tions in this gene have been implicated in hereditary non-polyposis co lorectal cancer (HNPCC). Alterations in the coding region of the hMSH- 2 gene result in a mutator phenotype with marked instability of micros atellite sequences, indicative of a deficiency in DNA repair. We have previously shown that a region of high homology between MutS proteins of different species containing a nucleotide binding domain, is suffic ient to bind DNA containing specific mismatched residues. In order to determine the minimal domain of hMSH-2 necessary for binding mismatch- containing oligonucleotides, deletion analysis of the (C) under bar-te rminal region was performed. We have constructed a 5' and 3' deletion series, expressed each deletion as a bacterial fusion protein and asse ssed it for ATPase activity and its ability to identify mismatch conta ining DNA. Here we demonstrate that a 585 bp fragment encoding 195 ami no acids within the (C) under bar-terminal domain of hMSH-2 is suffici ent to bind to DNA containing mismatches. (C) 1997 Academic Press.