DOMAIN ORGANIZATION AND FUNCTIONAL-ANALYSIS OF THERMUS-THERMOPHILUS MUTS PROTEIN

MutS protein binds to DNA and specifically recognizes mismatched or sm all looped out heteroduplex DNA. In order to elucidate its structure-f unction relationships, the domain structure of Thermus thermophilus Mu tS protein was studied by performing denaturation experiments and limi ted proteolysis. The former suggested that T.thermophilus MutS consist s of at least three domains with estimated stabilities of 12.3, 22.9 a nd 30.7 kcal/mol and the latter revealed that it consists of four doma ins: A1 (N-terminus to residue 130), A2 (131-274), B (275-570) and C ( 571 to C-terminus). A gel retardation assay indicated that T.thermophi lus MutS interacts non-specifically with double-stranded (ds), but not single-stranded DNA. Among the proteolytic fragments, the B domain bo und to dsDNA. On the basis of these results we have proposed the domai n organization of T.thermophilus MutS and putative roles of these doma ins.