Formate hydrogenlyase, formic acid translocation and hydrogen production: dynamic membrane biology during fermentation

Functional expression of a Mo-dependent formate dehydrogenase inEscherichia coliunder aerobic conditions

“…Interestingly, one mutation ( focA F7C) was fixed in isolates obtained from both evolved populations from UOF1 and UOF2 independent cultures. The pH-dependent channel FocA plays an important role in the regulation of intracellular formate concentration, notably during mixed-acid fermentation [23, 24]. We tested the impact of focA mutations F7C (isolate G5823) and V97I (isolate G5848) on formate-dependent growth by exchanging the mutated with the wild type focA allele in the two isolates.…”

Process Cascade for the Production of Green Polymers from CO2 and Electric Energy

“…As commonly known for organic acids, the protonated acids (i.e. formic acid) are membrane-soluble and can enter the cells simply by diffusion [34,35] (Fig. 6A).…”

Perspective elucidating the physiology of a microbial cell: Neidhardt's Holy Grail

“…This is also the case for Escherichia coli , which can use its conjugate base, formate, as an electron source for respiration with oxygen or nitrate as an acceptor, or during fermentation, where it is imported into the cell by the formate‐nitrite transporter channel protein, FocA (Kammel et al, 2022). In the cytoplasm, formic acid is disproportionated to CO 2 and H 2 by the membrane‐associated formate hydrogenlyase (FHL) complex (Peters & Sargent, 2023; Steinhilper et al, 2022). The benefits to the cell of taking up formate are two‐fold: first, if formic acid is imported into the cell, this helps offset acidification of the cell's immediate environment (Metcalfe et al, 2022); second, if formate, rather than formic acid, is taken up and subsequently formate plus a cytoplasmic proton are converted into gaseous H 2 plus CO 2 by the FHL complex (Peters & Sargent, 2023), then this helps offset acidification of the cytoplasm and, additionally, potentially contributes to the establishment of an ion (proton) gradient (Kammel et al, 2022).…”

“…In the cytoplasm, formic acid is disproportionated to CO 2 and H 2 by the membrane‐associated formate hydrogenlyase (FHL) complex (Peters & Sargent, 2023; Steinhilper et al, 2022). The benefits to the cell of taking up formate are two‐fold: first, if formic acid is imported into the cell, this helps offset acidification of the cell's immediate environment (Metcalfe et al, 2022); second, if formate, rather than formic acid, is taken up and subsequently formate plus a cytoplasmic proton are converted into gaseous H 2 plus CO 2 by the FHL complex (Peters & Sargent, 2023), then this helps offset acidification of the cytoplasm and, additionally, potentially contributes to the establishment of an ion (proton) gradient (Kammel et al, 2022). If the complex I‐related FHL complex can also pump a proton across the membrane during this reaction, all the better for the cell; however, it is currently still debated whether this latter step occurs (Peters & Sargent, 2023).…”

“…The benefits to the cell of taking up formate are two‐fold: first, if formic acid is imported into the cell, this helps offset acidification of the cell's immediate environment (Metcalfe et al, 2022); second, if formate, rather than formic acid, is taken up and subsequently formate plus a cytoplasmic proton are converted into gaseous H 2 plus CO 2 by the FHL complex (Peters & Sargent, 2023), then this helps offset acidification of the cytoplasm and, additionally, potentially contributes to the establishment of an ion (proton) gradient (Kammel et al, 2022). If the complex I‐related FHL complex can also pump a proton across the membrane during this reaction, all the better for the cell; however, it is currently still debated whether this latter step occurs (Peters & Sargent, 2023). The archeon Thermococcus onnurineus grows by formate‐driven H 2 production and uses a version of the FHL complex along with a FocA homolog to achieve this; however, the precise mechanistic details of how it grows at this apparent thermodynamic “energy limit” remain to be resolved (Kim et al, 2010).…”