Figure 2.

Mqo2 is responsible for the elusive S. aureus iLDH activity. (A) Genetic organization of the two annotated malate-quinone oxidoreductase genes. mqo1 is between an l-lactate permease and a hypothetical gene, while mqo2 is found between a putative acetyl-CoA synthase (acs, SACOL2624) and a class I fructose 1,6-bisphosphate aldolase, fdaB. (B) Specifically combining a Δmqo2 mutation to the Δldh1Δldh2 background abolishes the ability to utilize l-lactate. Cells were grown aerobically in chemically defined medium with 0.2% l-lactate as the primary carbon source. Residual growth on medium components was subtracted out of depicted curves (see Materials and Methods). (C) The l-lactate excreted following NO·-exposure cannot be reassimilated in a Δmqo2 mutant. Cells were grown in chemically defined medium as described in Figure 1B.