Fig 4.

Studies on the soluble heterodisulfide reductase HdrABC during growth on methanol. (A) Hypothesized bifurcation mechanism of the soluble heterodisulfide reductase HdrABC during growth on methylotrophic substrates in M. acetivorans. The alternative hypothesis is that the reaction does not involve F₄₂₀ (dashed lines). formmfr(b), formylmethanofuran(b). (B) Flux balance analysis predicts that during growth on methylotrophic substrates (methanol shown), HdrABC is not used when Rnf is available, but a Δrnf mutant is predicted to carry flux through HdrABC. The growth rate for the Δrnf mutant is predicted to be about 20% less than that for the wild type with bifurcation and 35% less without.