A dual-signaling mechanism mediated by the ArcB hybrid sensor kinase containing the histidine-containing phosphotransfer domain in Escherichia coli.
The two components ArcB and ArcA play a crucial role in the signal transduction implicated in the complex transcriptional regulatory network that allows Escherichia coli to sense various respiratory growth conditions. ArcB is a hybrid sensor kinase having multiple phosphorylation sites in its primary amino acid sequence, including a transmitter, a receiver, and a histidine-containing phosphotransfer (HPt) domain. ArcA is a DNA-binding transcriptional regulator with a receiver domain. Results of recent in vitro studies revealed multistep His-to-Asp phosphotransfer circuitry in the ArcB-ArcA signaling system. For this report we conducted a series of in vivo experiments using a set of crucial ArcB mutants to evaluate the regulation of the sdh operon. The results suggested that the phosphorylated His-717 site in the HPt domain of ArcB is essential for anaerobic repression of sdh. Nonetheless, the ArcB mutant lacking this crucial His-717 site does not necessarily exhibit a null phenotype with respect to ArcB-ArcA signaling. The HPt mutant appears to maintain an ability to signal ArcA, particularly under aerobic conditions, which results in a significant repression of sdh. Based on these and other in vivo results, we propose a model in which ArcB functions in its own right as a dual-signaling sensor that is capable of propagating two types of stimuli through two distinct phosphotransfer pathways.
Matsushika
A
A
Laboratory of Molecular Microbiology, School of Agriculture, Nagoya University, Chikusa-ku, Nagoya 464-8601, Japan.
Mizuno
T
T
D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics / Q000502:physiology*; D029968:Escherichia coli Proteins; D015964:Gene Expression Regulation, Bacterial; D006639:Histidine; D008565:Membrane Proteins / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D009876:Operon; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000378:metabolism*; D010766:Phosphorylation; D011494:Protein Kinases; D055503:Protein Multimerization; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D012097:Repressor Proteins; D015398:Signal Transduction
D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; C041610:arcA protein, E coli; D006639:Histidine; D011494:Protein Kinases; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; C065271:arcB protein, E coli