We genetically characterized the Pseudomonas putida mutS gene and found tha
t it encodes a smaller MutS protein than do the genes of other bacteria. Th
is gene is able to function in the mutS mutants of Escherichia coli and Bac
illus subtilis. A P. putida mutS mutant has a mutation frequency 1,000-fold
greater than that of the wild-type strain.