THE GROE GENE-PRODUCTS OF ESCHERICHIA-COLI ARE DISPENSABLE FOR MUCA(+)B(+)-DEPENDENT UV MUTAGENESIS

UV mutagenesis in Escherichia coli requires the groES(+)EL(+) chaperonins as well as the umuD(+)C(+) SOS-regulated genes. GroES and GroEL appear to be required to stabilize UmuC. The mucA(+)B(+) genes, which are encoded on a broad host range plasmid, are functionally analogous and structurally similar to the umuD(+)C(+) genes of E. coli. While these gene pairs are quite similar, differences have been reported in the functioning of these gene products. We tested whether mucA(+)B(+) function requires the groE(+) gene products as well. We show that mucA(+)B(+)-induced UV mutagenesis, UV resistance, phage reactivation and cold sensitivity do not require the groE(+) heat shock genes. These findings suggest that the requirement of UmuC for groES(+)EL(+) function is not shared by its analog, MucB.