Abstract
Two proteins with MW of 61,000 and 73,000 were induced by UV light in E. coli mutants in which the SOS responses are constitutively expressed. The induction of these proteins by UV light and nalidixic acid is independent on the recA+ lexA+ regulatory system. Analysis of these proteins by 2-dimensional gel electrophoresis and comparison with the heat-shock proteins of E. coli revealed that the MW 61,000 protein comigrated with the groEL gene product, that the MW 73,000 protein comigrated with the dnaK gene product and that other heat-shock proteins was also induced. The induction of groEL and dnaK by UV light and nalidixic acid is controlled by the htpR locus. The regulatory response of E. coli to agents such as UV light and nalidixic acid is apparently more complex than previously thought.