FOF1-ATPase mediates regulation of fermentation and energy metabolism at pH 5.5
Heghine Gevorgyan, Karen A. Trchounian · 2025 · 7 citationsRead the paper
The activity of FOF1-ATP synthase (FOF1) is vital for the survival and anaerobic growth under acidic conditions providing efficient metabolism and energy for cellular function. This study demonstrated the role of FOF1-ATPase in the metabolic pathways and regulation of proton motive force in Escherichia coli at pH 5.5 during the fermentation of glucose, glycerol and formate. Alteration of the ratio of fermentation end-products was shown. The possible mechanisms for efficient energy utilization in cells lacking FOF1 were shown. It is suggested that Fdh-H transfers H+ from formate to Hyd, which serves not only for H₂ generation but also for H+ cycling to FOF1 or directly to FOF1 in cells grown for 20 h. The interaction between H2 and H+ cycling was proposed as an essential mechanism for balancing ΔpH at acidic conditions. FOF1-ATPase was identified to play a pivotal role in forming both components of Δp at 20 h and 72 h.
What the full text shows
Shown in the lab- FOF1-ATPase deficiency (DK8 strain) significantly reduces glycerol utilization rate. — 0.06 mM h−1 vs. 0.31 mM h−1 in WT (pH 5.5, 6–72 h growth)
- FOF1-ATPase deficiency leads to increased acetate production. — ~3.1 mM higher than WT at 20 h (pH 5.5)
- FOF1-ATPase deficiency suppresses ethanol synthesis and reduces lactate/succinate generation. — Ethanol completely suppressed (pH 5.5, glucose as primary carbon source (3–24 h))
- FOF1-ATPase deficiency increases membrane potential (ΔΨ). — ~28 mV higher at 20 h and ~25 mV higher at 72 h vs. WT (pH 5.5)
- FOF1-ATPase deficiency increases proton motive force (Δp) at late growth stages. — ~38 mV increase at 72 h vs. WT (pH 5.5)
- FOF1-ATPase deficiency severely reduces hydrogenase (Hyd) activity. — ~90% reduction at 20 h (~20 mU (mg protein)−1 vs. ~240 mU (mg protein)−1 in WT) (pH 5.5)
- Setup
- E. coli MC 4100 (WT) and DK8 (ΔatpB-atpC) mutant grown anaerobically at pH 5.5 in peptone medium supplemented with glucose (11.1 mM), glycerol (137 mM), and sodium formate (10 mM).
- How
- The study compared wild-type E. coli and a FOF1-ATPase deficient mutant (DK8) using HPLC for substrate/product analysis, gas chromatography for H2, and ion-selective electrodes for H+ and K+ fluxes. Bioenergetic parameters (ΔpH, ΔΨ, Δp) were measured using 9-aminoacridine fluorescence and tetraphenylphosphonium distribution.
- Limitations
- Results are specific to anaerobic fermentation conditions. · The role of Fdh-H in H+ cycling is hypothesized rather than directly proven. · Lack of transcriptomic or proteomic data to explain metabolic reprogramming.
Summarized by Gemma 4 from the open-access full text · 8 Oct 2026. Read it