Proton conductance and regulation of proton/potassium fluxes in Escherichia coli FhlA-lacking cells during fermentation of mixed carbon sources

Heghine Gevorgyan; Anna Poladyan; Karen Trchounian; Anait Vassilian

doi:10.1016/j.abb.2024.109999

Proton conductance and regulation of proton/potassium fluxes in Escherichia coli FhlA-lacking cells during fermentation of mixed carbon sources

Arch Biochem Biophys. 2024 May:755:109999. doi: 10.1016/j.abb.2024.109999. Epub 2024 Apr 15.

Authors

Heghine Gevorgyan¹, Anna Poladyan², Karen Trchounian³, Anait Vassilian⁴

Affiliations

¹ Department of Biochemistry, Microbiology and Biotechnology, Faculty of Biology, Yerevan State University, 0025, Yerevan, Armenia; Research Institute of Biology, Faculty of Biology, Yerevan State University, 0025, Yerevan, Armenia; Microbial Biotechnologies and Biofuel Innovation Center, Yerevan State University, 0025, Yerevan, Armenia.
² Department of Biochemistry, Microbiology and Biotechnology, Faculty of Biology, Yerevan State University, 0025, Yerevan, Armenia; Research Institute of Biology, Faculty of Biology, Yerevan State University, 0025, Yerevan, Armenia. Electronic address: apoladyan@ysu.am.
³ Department of Biochemistry, Microbiology and Biotechnology, Faculty of Biology, Yerevan State University, 0025, Yerevan, Armenia; Research Institute of Biology, Faculty of Biology, Yerevan State University, 0025, Yerevan, Armenia; Microbial Biotechnologies and Biofuel Innovation Center, Yerevan State University, 0025, Yerevan, Armenia. Electronic address: k.trchounian@ysu.am.
⁴ Research Institute of Biology, Faculty of Biology, Yerevan State University, 0025, Yerevan, Armenia.

PMID: 38621444
DOI: 10.1016/j.abb.2024.109999

Abstract

Escherichia coli uptake potassium ions with the coupling of proton efflux and energy utilization via proton F_OF₁-ATPase. In this study contribution of formate hydrogen lyase (FHL) complexes in the proton/potassium fluxes and the formation of proton conductance (C_MH⁺) were investigated using fhlA mutant strain. The proton flux rate (J_H+) decreased in fhlA by ∼ 25 % and ∼70 % during the utilization of glucose and glycerol, respectively, at 20 h suggesting H⁺ transport via or through FHL complexes. The decrease in J_K+ in fhlA by ∼40 % proposed the interaction between FHL and Trk secondary transport system during mixed carbon fermentation. Moreover, the usage of N,N'-dicyclohexylcarbodiimide (DCCD) demonstrated the mediation of F_OF₁-ATPase in this interaction. C_MH⁺ was 13.4 nmol min^-1 mV^-1 in WT at 20 h, which decreased by 20 % in fhlA. Taken together, FHL complexes have a significant contribution to the modulation of H⁺/K⁺ fluxes and the C_MH ⁺ for efficient energy transduction and regulation of the proton motive force during mixed carbon sources fermentation.

Keywords: Escherichia coli; Formate hydrogen lyase; Proton conductance; Proton motive force; Proton/potassium fluxes.