Bacterial Adaptation of Respiration from Oxic to Microoxic and Anoxic Conditions: Redox Control

Abstract

Under a shortage of oxygen, bacterial growth can be faced mainly by two ATP-generating mechanisms: (i) by synthesis of specific high-affinity terminal oxidases that allow bacteria to use traces of oxygen or (ii) by utilizing other substrates as final electron acceptors such as nitrate, which can be reduced to dinitrogen gas through denitrification or to ammonium. This bacterial respiratory shift from oxic to microoxic and anoxic conditions requires a regulatory strategy which ensures that cells can sense and respond to changes in oxygen tension and to the availability of other electron acceptors. Bacteria can sense oxygen by direct interaction of this molecule with a membrane protein receptor (e.g., FixL) or by interaction with a cytoplasmic transcriptional factor (e.g., Fnr). A third type of oxygen perception is based on sensing changes in redox state of molecules within the cell. Redox-responsive regulatory systems (e.g., ArcBA, RegBA/PrrBA, RoxSR, RegSR, ActSR, ResDE, and Rex) integrate the response to multiple signals (e.g., ubiquinone, menaquinone, redox active cysteine, electron transport to terminal oxidases, and NAD/NADH) and activate or repress target genes to coordinate the adaptation of bacterial respiration from oxic to anoxic conditions. Here, we provide a compilation of the current knowledge about proteins and regulatory networks involved in the redox control of the respiratory adaptation of different bacterial species to microxic and anoxic environments.

The Terminal Oxidase cbb 3 Functions in Redox Control of Magnetite Biomineralization in Magnetospirillum gryphiswaldense

“…cbb 3 and aa 3 oxidases, encoded by their respective operons ccoNOQP and coxBAC, belong to the family of cytochrome c oxidases. In some bacteria, aa 3 is the predominant oxidase under O 2 -rich growth conditions, whereas cbb 3 is expressed only under conditions of O 2 limitation (27). Although ccoNOQP operons are also present in other MTB, including M. magneticum, M. magnetotacticum, and Mc.…”

“…Since the three putative terminal oxidases in other bacteria were reported previously to show distinct affinities for oxygen and thus exhibit their maximum expression levels at different oxygen concentrations (27), we tested their expression patterns in WT MSR-1 under different conditions (Fig. 1B).…”

Assembly pathway of a bacterial complex iron sulfur molybdoenzyme

“…In addition to oxygen, bacteria can exploit a myriad of substrates as terminal electron acceptors for respiration in anaerobic environments. Respiratory redox enzymes catalyze these oxidation/reduction reactions by transferring electrons from a donor to an acceptor molecule, most often operating at the cytoplasmic membrane by forming a redox loop between periplasmic and cytoplasmic enzymes connected by the quinone pool (3,4). The facultative anaerobic model organism, Escherichia coli, has a variety of characterized anaerobic electron acceptors that include nitrate (NO 3 − ), nitrite (NO 2 − ), fumarate (C 4 H 4 O 4 ), trimethylamine N-oxide [(CH 3 ) 3 NO, TMAO] and dimethyl sulfoxide [(CH 3 ) 2 …”

El rol de la respiración aeróbica en el ciclo de vida de <em>Escherichia coli</em>: Implicaciones para la salud pública

“…Escherichia coli, and other members of the family Enterobacteriaceae, use different metabolic pathways (anaerobic respiration, microaerobic respiration and fermentation) to obtain energy from organic compounds (in animal's guts), under either low oxygen or anaerobic conditions [4][5][6]; therefore it is intriguing that aerobic respiration is a universal property in E. coli strains.…”

“…Although aerobic respiration is the most efficient way to obtain energy from organic matter [3,4], it is energetically demanding as it requires many genes and the synthesis of several molecules that are part of complex systems such as: signal transduction, gene transcription and electron transport [1,4,6]. It is paradoxical that a bacterium which replicates mainly in a microaerophilic and anaerobic habitats, conserves genes for growth under fully aerobic conditions; bacterial genes are prone to inactivation unless there is a strong selective pressure…”