arcA (dye), a global regulatory gene in Escherichia coli mediating repression of enzymes in aerobic pathways.

Abstract

In Escherichia coli the levels of numerous enzymes associated with aerobic metabolism are decreased during anaerobic growth. In an arcA mutant the anaerobic levels of these enzymes are increased. The enzymes, which are encoded by different regulons, include members that belong to the tricarboxylic acid cycle, the glyoxylate shunt, the pathway for fatty acid degradation, several dehydrogenases of the flavoprotein class, and the cytochrome o oxidase complex. Transductional crosses placed the arcA gene near min o on the chromosomal map. Complementation tests showed that the arcA gene corresponded to the dye gene, which is also known as fexA, msp, seg, or sfrA because of various phenotypic properties [Bachmann, B. (1983) Microbiol. Rev. 47, 180-230].A dye-deletion mutant was derepressed in the aerobic enzyme system. The term modulon is proposed to describe a set of regulons that are subject to a common transcriptional control.In facultative anaerobes such as Escherichia coli, the network for electron transport is organized in such a way that the energetically most favorable pathway is used. On the basis of the regulatory patterns of gene expression, these networks appear to be three main hierarchical systems. The aerobic respiratory pathways conduct the flow of electrons (or reducing equivalents) to 02 (E"' = + 0.82 V). In the absence of 02, nitrate (E"' = + 0.42 V) can be used. In this first system ubiquinone (E"' = +0.1 V) acts as an adapter and passes the electrons to the 02 or nitrate acceptor chain.The next preferred system conducts electrons to terminal acceptors such as trimethylamine N-oxide (E ' = + 0.13 V) or fumarate (E"' = +0.03 V), with menaquinone (E"' = -0.074 V) as the adapter. Both respiratory pathways supply the cell with metabolic energy by generating proton-motive force across the cytoplasmic membrane. As the operation of these pathways is curtailed by the shortage of exogenous electron acceptors, the cell relies increasingly on the energetically least rewarding system, in which redox reactions are balanced by fermentative dismutation of carbon and energy sources. The pyridine nucleotides serve as the adapter for the transfer of electrons, and substrate-level phosphorylation becomes the principal means of energy generation. The choice of the redox pathways is biased in favor of those that provide the greatest difference in midpoint potential between the initial electron donor and the terminal acceptor, for this difference limits the amount of energy that can be harnessed (for reviews see refs. 1 and 2).The flow of electrons through the three main redox systems and the channeling within each is guided by a complex set of controls that include the regulation of gene expression. Thus, 02 respiration interferes with induction of the anaerobic respiratory system. The mechanism of this control is beginning to be understood. (4). The apo-repressor may be encoded by the narL gene (5), which also acts as an activator for the synthesis of nitrate reductase (6). The mechanisms by which enzymes that...

Aerobic regulation of cytochrome d oxidase (cydAB ) operon expression in Escherichia coli: roles of Fnr and ArcA in repression and activation

“…To create the ⌬arcA and ⌬fnr ⌬arcA strains (PC35 and PC36), the ⌬arcA allele from PC35 was transduced into the MC4100 and PC2 lysogens by P1 transduction. The resulting ⌬arcA strains were confirmed as arcA ¹ by their diminished growth on toluidine blue dye plates (Iuchi and Lin, 1988;Cotter and Gunsalus, 1992).…”

Identification of metabolic engineering targets for the enhancement of 1,4-butanediol production in recombinant E. coli using large-scale kinetic models

“…Notable modifications include deletions in adhE, ldhA, pflB, mdh, and mutated versions of gltA, lpdA, and arcA. The arcA mutation, resulting in an 8 amino acid insertion in the ArcA protein (Iuchi and Lin, 1988;Silverman et al, 1991) renders the regulator largely inactive, and thus activates the oxidative TCA flux under low O2 conditions (Yim et al, 2011). The gltA and lpdA mutations are the same as described in (Yim et al, 2011).…”

Role of multiple ArcA recognition sites in anaerobic regulation of succinate dehydrogenase (sdhCDAB ) gene expression in Escherichia coli

“…Expression of the sdhCDAB genes is regulated in response to oxygen availability and by the richness of the cell growth medium (Iuchi et al, 1994;Park et al, 1995a). Mutations in arcA were shown to result in elevated SDH enzyme levels under anaerobic conditions and, to a limited extent, under aerobic conditions (Iuchi and Lin, 1988). Strains defective in the arcA gene are also altered in the production of other enzymes of the TCA cycle, the aerobic respiratory enzymes, cytochrome o and cytochrome d oxidase, and enzymes involved in pyruvate cleavage, fatty acid degradation and superoxide dismutase synthesis (Iuchi and Lin, 1988;Fu et al, 1991;Tardat and Touati, 1991;Cotter and Gunsalus, 1992;Gunsalus and Park, 1994;Cotter et al, 1997).…”