# The role of Escherichia coli FhlA transcriptional activator in generation of proton motive force and FF-ATPase activity at pH 7.5.
> 大腸菌FhlA転写活性化因子がプロトン駆動力およびFF-ATPase活性に果たす役割（pH 7.5条件下）


## Abstract

Escherichia coli generates molecular hydrogen through formate hydrogen lyase (FHL) complexes when grown on mixed carbon sources. This study examined the role of FhlA, the transcriptional activator of the formate regulon, in fermentation product formation and proton motive force (Δp) generation during growth on glucose, glycerol, and formate mixtures at 20 and 72 hours. The fhlA deletion mutant exhibited a specific growth rate approximately 1.5-fold lower than the wild type, and DCCD—an ATPase inhibitor—abolished growth only in the mutant. Formate was not consumed by the fhlA mutant, whereas wild-type cells co-utilized formate and glucose. DCCD-sensitive ATPase activity in membrane vesicles rose roughly 2-fold in wild-type cells at 72 hours but declined by 70% in the mutant. FhlA absence primarily disrupted the ΔpH component of Δp at 72 hours. Wild-type Δp decreased by approximately 40 mV between 24 and 72 hours, while the mutant maintained a stable Δp. These findings indicate that FhlA modulates fermentation end-product concentrations and supports proton motive force generation through its influence on FF-ATPase activity.

### Mechanism

FhlA activates the formate regulon, regulating FF-ATPase activity and thereby contributing to proton motive force generation primarily through modulation of the ΔpH component during fermentative growth.

## Bibliographic

- **Authors**: Gevorgyan H, Khalatyan S, Vassilian A, Trchounian K
- **Journal**: IUBMB Life
- **Year**: 2021
- **PMID**: [33773019](https://pubmed.ncbi.nlm.nih.gov/33773019/)
- **DOI**: [10.1002/iub.2470](https://doi.org/10.1002/iub.2470)
- **Study type**: in vitro study
- **Delivery route**: in vitro
- **Effect reported**: not assessed

## Delivery context

This is basic research at the cellular or molecular level. For human application, inhalation is the most promising delivery route, but inhalation carries explosion risk and concentration matters (empirical LFL of 10%; high-concentration devices are not recommended).

## Safety notes

This is basic research at the cellular or molecular level. For human application, inhalation is the most promising delivery route, but inhalation carries explosion risk and concentration matters (empirical LFL of 10%; high-concentration devices are not recommended).

See also:
- [Inhalation concentration and LFL / UFL](https://h2-papers.org/en/safety-notes/inhalation-concentration)
- [Consumer Affairs Agency accident cases](https://h2-papers.org/en/safety-notes/accident-cases)
- [Inhalation safety threshold lineage](https://h2-papers.org/en/safety-notes/lineage)

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> **Cite as**: H2 Papers — PMID 33773019. https://h2-papers.org/en/papers/33773019
> **Source**: PubMed PMID [33773019](https://pubmed.ncbi.nlm.nih.gov/33773019/)