CheA protein, a central regulator of bacterial chemotaxis, belongs to a family of proteins that control gene expression in response to changing environmental conditions.

Abstract

During bacterial chemotaxis, the binding of stimulatory ligands to chemoreceptors at the cell periphery leads to a response at the flagellar motor. Three proteins appear to be required for receptor-mediated control of swimming behavior, the products of the cheA, cheW, and cheY genes. Here we present the complete nucleotide sequence of the Salmonella lyphimurium cheA gene together with the purification and characterization of its protein product. The protein is a 73,000 M, cytoplasmic constituent. Amino acid-sequence comparisons indicate that it belongs to a family of bacterial regulatory proteins including the products of the cpxA, deWf, envZ, ntrB, phoR, phoM, and virA genes. Each member of this family has a conserved domain of -200 residues within its C terminus. We have previously shown that another chemotaxis protein, CheY, represents a domain of protein structure that has been conserved within a second large family of bacterial regulatory proteins. Each protein of the CheA family seems to function as a regulator of a different CheY homologue. Although each pair of proteins appears to produce a specialized response to a distinct type of stimulus, the relationships in primary structure suggest that a similar molecular mechanism may be involved.During bacterial chemotaxis, receptor proteins at the cell surface modulate motor behavior in response to binding of extracellular ligands (for reviews, see refs.

Analysis of a chemotaxis operon from Rhodospirillum centenum

“…A portion of cheA from R. centenum was isolated by PCR amplification using degenerate oligonucleotide primers deduced from the highly conserved N and G2 blocks (26) in CheA sequences from E. coli, Salmonella typhimurium, Bacillus subtilis, Myxococcus xanthus, and Enterobacter aerogenes (6,9,20,24,39 (Fig. 1).…”

The Critical Role of the Conserved Thr247 Residue in the Functioning of the Osmosensor EnvZ, a Histidine Kinase/Phosphatase, in Escherichia coli

“…Response regulators can use small molecule phosphodonors such as phosphoramidate and acetyl phosphate directly (48,49). The half-lives of phosphoaspartate groups under denaturing conditions are generally much longer (49,51) than those observed with the native response regulator proteins when such studies have been conducted (40,50,52). Therefore, the role of histidine kinases in the dephosphorylation of their phosphorylated response regulators has often been considered to be just the modulation of the autophosphatase activity of the response regulator.…”

Interactions between Escherichia coliNucleoside-diphosphate Kinase and DNA

“…CheA was purified as described previously (24). A truncated EnvZ protein (EnvZ115) in which the first 38 amino acids of EnvZ are replaced with 8 amino acids of LacZ (25), EnvZ N342K mutant protein (26), and OmpR fused to the maltose-binding protein (OmpR-MBP) were all gifts from T. Silhavy (Princeton University).…”