Gevorgyan Heghine, Khalatyan Satenik, Vassilian Anait, Trchounian Karen
Department of Biochemistry, Microbiology and Biotechnology, Faculty of Biology, Yerevan State University, Yerevan, Armenia.
Faculty of Biology, Scientific-Research Institute of Biology, Yerevan State University, Yerevan, Armenia.
IUBMB Life. 2021 Jun;73(6):883-892. doi: 10.1002/iub.2470. Epub 2021 Apr 7.
Escherichia coli is able to utilize the mixture of carbon sources and produce molecular hydrogen (H ) via formate hydrogen lyase (FHL) complexes. In current work role of transcriptional activator of formate regulon FhlA in generation of fermentation end products and proton motive force, N'N'-dicyclohexylcarbodiimide (DCCD)-sensitive ATPase activity at 20 and 72 hr growth during utilization of mixture of glucose, glycerol, and formate were investigated. It was shown that in fhlA mutant specific growth rate was ~1.5 fold lower compared to wt, while addition of DCCD abolished the growth in fhlA but not in wt. Formate was not utilized in fhlA mutant but wt cells simultaneously utilized formate with glucose. Glycerol utilization started earlier (from 2 hr) in fhlA than in wt. The DCCD-sensitive ATPase activity in wt cells membrane vesicles increased ~2 fold at 72 hr and was decreased 70% in fhlA. Addition of formate in the assays increased proton ATPase activity in wt and mutant strain. FhlA absence mainly affected the ΔpH but not ΔΨ component of Δp in the cells grown at 72 hr but not in 24 hr. The Δp in wt cells decreased from 24 to 72 hr of growth ~40 mV while in fhlA mutant it was stable. Taken together, it is suggested that FhlA regulates the concentration of fermentation end products and via influencing F F -ATPase activity contributes to the proton motive force generation.
大肠杆菌能够利用碳源混合物，并通过甲酸氢裂解酶（FHL）复合物产生分子氢（H₂）。在当前的工作中，研究了甲酸调节子FhlA的转录激活因子在发酵终产物生成和质子动力势中的作用，以及在利用葡萄糖、甘油和甲酸混合物生长20小时和72小时时对N,N'-二环己基碳二亚胺（DCCD）敏感的ATP酶活性。结果表明，与野生型相比，fhlA突变体的比生长速率低约1.5倍，而添加DCCD可消除fhlA突变体的生长，但对野生型无影响。fhlA突变体不能利用甲酸，而野生型细胞能同时利用甲酸和葡萄糖。fhlA突变体中甘油的利用比野生型更早开始（从2小时开始）。野生型细胞膜囊泡中对DCCD敏感的ATP酶活性在72小时时增加约2倍，而在fhlA突变体中降低了70%。在测定中添加甲酸可增加野生型和突变株中的质子ATP酶活性。在72小时生长的细胞中，缺失FhlA主要影响Δp的ΔpH成分，而不影响ΔΨ成分，但在24小时生长的细胞中则无此影响。野生型细胞生长从24小时到72小时时，Δp降低约40 mV，而fhlA突变体中的Δp则保持稳定。综上所述，表明FhlA调节发酵终产物的浓度，并通过影响F₀F₁-ATP酶活性促进质子动力势的产生。
