Differentiation between mutants of Escherichia coli K defective in oxidative phosphorylation

Abstract

Hybrid membrane particles from two mutants of Escherichia coli K12, Bv4 and K11, defective in oxidative phosphorylation, have been prepared, in which ATP-driven membrane energization is restored. A soluble factor of mutant K11 was found to have properties similar to parental crude coupling factor, ATPase (EC 3.6.1.3). Membrane particles of this mutant could not be reconstituted by parental coupling factor. Either parental coupling factor, or the soluble factor of mutant K11 could reconstitute both respiration-driven and ATP-driven energization to membrane particles of mutant Bv14 or to parental particles depleted of ATPase. Mutant Bv4 was found to be devoid of coupoing factor activity, while retaining the ability to hydrolyze ATP. Both mutants possess an ATPase with an altered binding to the membrane. Mutant K11 is impaired in respiration-driven amino acid transport, in contrast to mutant Bv4. The three major subunits of parental Escherichia coli ATPase have been isolated and antibodies have been prepared against these subunits. Antibodies against the largest subunit (alpha component) or against the intact catalytic subunits (alpha + beta components) inhibit both ATP-Pi exchange in the parent organism as well as ATP hydrolytic activity in parent and mutants. Antibodies against the two other subunits (beta or gamma components) also inhibit these two reactions, but were found to be less effective. Mutant N144, which lacks ATPase activity, shows no precipitin lines with anti-alpha, anti-beta, anti-gamma, or anti (alpha + beta) preparations. In contrast, mutants Bv4 and K11, exhibit cross-reactivity with all of the antisera.