Synthesis and sideedness of membrane-bound respiratory nitrate reductase (EC1.7.99.4) in Escherichia coli lacking cytochromes.

The synthesis of nitrate reductase and its incorporation into the cytoplasmic membrane of Escherichia coli strain A1004a (5-aminolaevulinic acid auxotroph) does not require synthesis of cytochrome b. The synthesis of the apoprotein(s) of the cytochrome b of the respiratory pathway from NADH to nitrate appears to be inhibited by the absence of haem. No member of the respiratory pathway from NADH to oxygen is capable of reducing nitrate reductase directly. The site on nitrate reductase that oxidizes FMNH2 is located on the cytoplasmic aspect of the cytoplasmic membrane.