Hemin Reconstitutes Proton Extrusion in an H + -ATPase-Negative Mutant of Lactococcus lactis

Abstract
H+-ATPase is considered essential for growth ofLactococcus lactis. However, media containing hemin restored the aerobic growth of an H+-ATPase-negative mutant, suggesting that hemin complements proton extrusion. We show that inverted membrane vesicles prepared from hemin-grown L. lactis cells are capable of coupling NADH oxidation to proton translocation.