SUMMARYMutations,sulAandsulB, that suppress the UV sensitivity conferred by thelonmutation have been isolated and precisely positioned on the linkage map ofEscherichia coli. TheE. coliB strains Bs-3 and Bs-8 have been shown to possesssulAmutations. Also theE. coliK12 strain J6271 that possesses a suppressor of thelonmutation, previously designated assuf, has been shown to be asulAmutation. A series of methylmethane sulphonate resistant derivatives of anE. coliK12lonstrain has been isolated and genetically characterized. In addition tosulAmutations, a second suppressorsulBwas identified and located betweenleuandazigenes on the chromosome. NeithersulAorsulBmutations result in increased sensitivity to the antibiotics ampicillin, rifampicin, or actinomyein D, nor do they have any significant effect upon the overproduction of mucopolysaccharide caused by thelonmutation. Under some growth conditions thesulBmutation causes cells to be temperature sensitive for the cell division process at 42 °C.
Cotranscription of the Escherichia coli isoleucyl-tRNA synthetase (ileS) and prolipoprotein signal peptidase (lsp) genes. Fine-structure mapping of the lsp internal promoter.
