STABILIZATION OF A HEMA-LACZ HYBRID PROTEIN AGAINST PROTEOLYSIS DURING CARBON STARVATION IN ATP MUTANTS OF SALMONELLA-TYPHIMURIUM

Transposon insertions that stabilize the beta-galactosidase activity o f a HemA-LacZ hybrid protein following carbon starvation were mapped t o the ntp operon of Salmonella typhimurium. This effect is similar to that seen with nuo mutants defective in the energy-conserving type I N ADH dehydrogenase, Insertions in several other genes, including such h ighly pleiotropic mutants as rpoS, polA, and hfq, were isolated with t he same phenotypic screen, but they do not affect the beta-galactosida se activity of HemA-LacZ, All of these mutants act indirectly to alter the colony color of many different fusion strains on indicator plates .