Kinase Activity of ArcB from Escherichia coli Is Subject to Regulation by Both Ubiquinone and Demethylmenaquinone

Abstract

Expression of the catabolic network in Escherichia coli is predominantly regulated, via oxygen availability, by the two-component system ArcBA. It has been shown that the kinase activity of ArcB is controlled by the redox state of two critical pairs of cysteines in dimers of the ArcB sensory kinase. Among the cellular components that control the redox state of these cysteines of ArcB are the quinones from the cytoplasmic membrane of the cell, which function in ‘respiratory’ electron transfer. This study is an effort to understand how the redox state of the quinone pool(s) is sensed by the cell via the ArcB kinase. We report the relationship between growth, quinone content, ubiquinone redox state, the level of ArcA phosphorylation, and the level of ArcA-dependent gene expression, in a number of mutants of E. coli with specific alterations in their set of quinones, under a range of physiological conditions. Our results provide experimental evidence for a previously formulated hypothesis that not only ubiquinone, but also demethylmenaquinone, can inactivate kinase activity of ArcB. Also, in a mutant strain that only contains demethylmenaquinone, the extent of ArcA phosphorylation can be modulated by the oxygen supply rate, which shows that demethylmenaquinone can also inactivate ArcB in its oxidized form. Furthermore, in batch cultures of a strain that contains ubiquinone as its only quinone species, we observed that the ArcA phosphorylation level closely followed the redox state of the ubiquinone/ubiquinol pool, much more strictly than it does in the wild type strain. Therefore, at low rates of oxygen supply in the wild type strain, the activity of ArcB may be inhibited by demethylmenaquinone, in spite of the fact that the ubiquinones are present in the ubiquinol form.

All Three Endogenous Quinone Species of Escherichia coli Are Involved in Controlling the Activity of the Aerobic/Anaerobic Response Regulator ArcA

“…This culture was used as a 0.1% inoculum for 25 ml cell cultures which were grown as anaerobic batch culture at 37°C using Evans’ salt medium with nitrilo-acetic acid (2 mM) and sodium phosphate buffer (100 mM, pH 7) to increase buffering capacity (Evans et al, 1970; Sharma et al, 2013). Glucose (20 mM) was used as carbon source and 50 mM DMSO was used as terminal electron acceptor.…”

Metabolism of long-chain fatty acids affects disulfide bond formation inEscherichia coliand activates envelope stress response pathways as a combat strategy

“…We observed accumulation of the reduced form of DsbA when LCFA-grown cells entered the stationary phase, which restored to the oxidized state in mid- and late-stationary phases of growth (Fig 4A). A previous study showed that during aerobic growth of E. coli (in minimal medium supplemented with glucose) an increase in cell density increases the ubiquinol/ubiquinone ratio due to a decrease in the availability of dissolved oxygen, and this ratio decreases later in stationary phase due to lowered metabolism [46]. Because LCFA metabolism produces a large number of electron donors, this would lead to a much larger increase in ubiquinol/ubiquinone ratio with an increase in cell density, thereby making ubiquinone less available for the oxidation of the disulfide bond-forming machinery.…”

Novel heavy metal resistance gene clusters are present in the genome of Cupriavidus neocaledonicus STM 6070, a new species of Mimosa pudica microsymbiont isolated from heavy-metal-rich mining site soil

“…These CH34 T clusters encode an RND system (czcICBA), the ZntA ATPase, a two-component regulatory system CzcRS and a 3-demethylubiquinone-9 3-methyltransferase (UbiG) [35,63]. UbiG participates in the biosynthesis of ubiquinone and its activity could be related to the sensor kinase activity of the twocomponent system CzcRS [78,79]. The czcL, hns and mmmQ genes encode an unknown protein, an H-NS like protein and a small stress responsive protein, respectively.…”