Differentiation of arcA, arcB, and cpxA mutant phenotypes of Escherichia coli by sex pilus formation and enzyme regulation

Abstract

In Escherichia coli, mutations in arcA (dye) or arcB anaerobically derepress the synthesis of a multitude of enzymes of aerobic function, and mutations in arcA or cpxA impair F-pilus formation. It is thought that arcA encodes a promoter-recognizing protein, whereas arcB and cpxA encode sensor proteins which interact with the arcA product. In this study we found that anaerobic growth of a wild-type F' strain decreased the synthesis of both the enzymes and the pilus. Although the two arcA mutants examined were both anaerobically derepressed in the enzymes and impaired in aerobic pilus formation as expected, one mutant hyperproduced the pilus anaerobically. The two arcB mutants examined showed normal pilus formation when grown aerobically. When grown anaerobically they developed more pili than the wild-type strain did when grown aerobically. When a cpxA mutant was examined for synthesis of two aerobic enzymes, normal regulation was found. The available data suggest the following. The arcA product anaerobically represses certain genes of aerobic function and activates certain genes related to F function. It appears that the arcB product senses the redox or energy state; absence of the gene function shifts the arcA product to the nonrepressive form for enzyme synthesis for aerobic pathways. The cpxA product, on the other hand, senses the sexual state; absence of the gene function shifts the arcA product to the inactive form for F-pilus synthesis.

Arc and Sfr functions of the Escherichia coli K-12 arcA gene product are genetically and physiologically separable

“…In the current model, the signal is acquired by the integral membrane protein ArcB, which then transduces the information to a form that can be read by the ArcA protein, which is the actual genetic regulator (15,16,19). We show here that tra gene expression is only slightly dependent on ArcB function(s), in agreement with earlier, qualitative observations by luchi et al (17). If ArcB is required to elicit ArcA activity, this result implies that the Arc and Sfr functions of the arcA gene product are separately regulated.…”

Phosphorylation and dephosphorylation of the NarQ, NarX, and NarL proteins of the nitrate-dependent two-component regulatory system of Escherichia coli

“…Aerobic and anaerobic regulation in E. coli is mediated in part by the ArcA/ArcB two-component system (13). A second sensor protein, CpxA, can also interact with ArcA (13,14) but in response to some signal other than that detected by ArcB. In a third example, the gene encoding a novel sensor protein, barA, was identified that shares a high degree of homology to both EnvZ and OmpR (25).…”

The ArcA/ArcB two‐component regulatory system of Escherichia coli is essential for Xer site‐specific recombination at psi

“…The arcA2 and arcB1 null alleles linked to Tn10 insertions (Iuchi et al, 1989b) were introduced into DS941 by P1 transduction. DS941 arcA2 was found to be almost completely defective in recombination at psi, whereas DS941 arcB1 was found 1 2 3 4 5 6 7 8 9 10 1 2 3 4 5 6 7 8 9 10 S P S P Fig.…”