Generation and regulation of the electrical membrane potential (Δψ) in Campylobacter jejuni, the major constituent of the proton motive force

The generation of an electrical membrane potential (Δψ), the major constituent of the proton motive force (pmf) is crucial for the ATP synthesis, bacterial growth and motility. The pmf drives the rotation of flagella and is vital for the microaerophilic human pathogen Campylobacter jejuni to colonize the mucus layer of the gut of warm-blooded animals. C. jejuni harbors a branched electron transport chain, enabling respiration with different electron donors and acceptors to generate a Δψ. Here, we demonstrate which electron donor/acceptor couples generate a Δψ and show the impact of the Δψ on the growth performance and motility of this bacterium. In the absence of both oxygen and formate or hydrogen, no Δψ is generated, which strongly reduced the growth rate and the number of motile bacteria. ATP generation is driven either by the pmf, or by substrate level phosphorylation if pyruvate is present. In response to low oxygen tension, C. jejuni upregulates the transcription of the alternative respiratory acceptor complexes and increases the transcription and activity of the donor complexes formate dehydrogenase (FdhABC) and hydrogenase (HydABCD). In conclusion, C. jejuni is dependent on oxygen as electron acceptor or formate/hydrogen as electron donor to generate a pmf that sustains efficient growth and motility performance. Overall design: Comparison of growth conditions, C. jejuni strain 81116 grown under microaerophilic (5% Oxygen) condition compared to C. jejuni strain 81116 grown under oxygen limited (0.3% oxygen) conditions with or without 10mM nitrate.

电膜电势（Δψ）的生成，作为质子动势（pmf）的主要成分，对于ATP合成、细菌生长及运动至关重要。pmf驱动鞭毛旋转，对于微需氧的人畜共患病原体空肠弯曲菌（Campylobacter jejuni）在温血动物肠道粘液层的定植具有至关重要的作用。C. jejuni携带分支电子传递链，能够与不同的电子供体和受体进行呼吸作用，从而产生Δψ。本研究旨在阐明哪些电子供体/受体偶联能生成Δψ，并展示Δψ对该细菌生长性能及运动能力的影响。在缺乏氧气和甲酸或氢气的情况下，无法生成Δψ，这显著降低了生长速率和运动细菌的数量。ATP的生成受pmf驱动，或由底物水平磷酸化驱动，前提是存在丙酮酸。在低氧张力的情况下，C. jejuni上调了替代呼吸受体复合物的转录，并增加了甲酸脱氢酶（FdhABC）和氢酶（HydABCD）供体复合物的转录和活性。总之，C. jejuni依赖于氧气作为电子受体或甲酸/氢气作为电子供体来生成维持高效生长和运动性能的pmf。总体设计：生长条件比较，将C. jejuni菌株81116在微需氧条件（5%氧气）下生长与在氧气限制条件（0.3%氧气）下生长，以及是否添加10mM硝酸盐的条件下生长进行比较。