Genes, enzymes and membrane proteins of the nitrate respiration system ofEscherichia coli.

A method was devised to isolate mutants carrying deletions through several genetic loci (chlD (+) andchlA (+)) which are involved in the membrane-bound nitrate respiratory complex ofEscherichia coli. Specific λ transducing phages were used to reintroduce these genes. Comparisons of membrane fractions from these transduced strains showed five membrane proteins that are necessary for the formation of an active nitrate respiration system. Two particular bacterial genes (chlD (+) andchlA (+)) were shown to control these five membrane proteins.Three of the proteins specified bychlA (+), appear to be constitutively controlled and always present in the membrane ofE. coli irrespective of growth conditions, while the other two proteins, specified bychlD (+), appear to be induced byanaerobic growth in the presence of nitrate.