Proteins induced by aerobiosis in Escherichia coli

Abstract

The role of protein induction and repression in the adaptation of E. coli to changes in the supply of O2 and other electron acceptors is only poorly understood. The changes in cellular protein composition associated with this adaptation was studied by measuring the levels of 170 individual polypeptides produced during aerobic or anaerobic growth of E. coli, with and without nitrate. Nineteen polypeptides had levels highest during aerobic growth. These proteins include the enzymes of the pyruvate dehydrogenase complex, several tricarboxylic acid cycle enzymes, superoxide dismutase and tetrahydropteroyltriglutamate transmethylase. The other aerobiosis-induced proteins were not identified. These polypeptides are major cellular proteins during aerobic growth and display several different patterns of regulation in response to medium composition. Induction ratios for O2 ranged from 2.2-11.2 with 1 exceptional member, superoxide dismutase, increasing 71-fold with aeration. Most of the proteins were also induced by nitrate during anaerobic growth. The time course of induction after shifts in O2 supply revealed similarities in response among proteins of related function or metabolic regulation class. These results are discussed in relation to previously reported information on the identified aerobiosis-induced proteins.