Dual chemotaxis signaling pathways in Bacillus subtilis: a sigma D-dependent gene encodes a novel protein with both CheW and CheY homologous domains

Abstract

The alternative sigma factor, aD, activates the expression of genes required for chemotaxis and motility in Bacillus subtilis, including those encoding flagellin, hook-associated proteins, and the motor proteins. The SD protein is encoded in a large operon which also encodes the structural proteins for the basal body and homologs of the enteric CheW, CheY, CheA, and CheB chemotaxis proteins. We report the identification and molecular characterization of a novel chemotaxis gene, cheV. The Chem. 267:12055-12060, 1992).The Bacillus subtilis alternative sigma factor, C D, activates the expression of a dozen or more operons required for chemotaxis and motility (for reviews, see references 14 and 31). The UD regulon is activated in late logarithmic growth during the transition to stationary phase (12,26). This socalled transition state is a time of complex decision making (41). The cell senses the nature of available nutrients and responds by the activation of numerous secondary metabolic processes, including genetic competence, degradative enzyme synthesis, antibiotic synthesis, and motility. Under appropriate conditions, a dormant endospore can be produced.Homologs of the B. subtilis CD protein (generically known as u28 factors) have been described for a variety of gram-positive and gram-negative bacteria, including Escherichia coli, Salmonella typhimurium, Pseudomonas aeruginosa, Vibrio parahaemolyticus, and Streptomyces coelicolor (7,14,24,39). With the interesting exception of S. coelicolor (7), these (u28 proteins all control expression of one or more flagellin genes. Sequence comparisons reveal that these uf factors form a closely related family of proteins known as the flagellar cluster (20). In addition, a great many other bacteria contain flagellin genes with promoter elements (P.) which predict the presence of a corresponding Cr28-like regulatory factor (14). Thus, the a 28 family of regulatory proteins appears to be broadly distributed.The extensive genetic characterization of the enterobacterial flagellar regulon provides us with our most complete picture of gene regulation by a member of the C28 family of proteins (21). The genes required for flagellar synthesis are transcriptionally activated in a complex hierarchy. The flhDC master regulators are expressed under the influence of the cyclic AMP receptor protein and are essential for the transcription of the class II * Corresponding author. Phone: (607) 255-3904. genes. One of the class II genes, fliA, encodes a uf factor (orF) homologous to B. subtilis oD (29). The aF protein, in turn, activates transcription of the class III flagellar and chemotaxis genes. The activity of oF is controlled by one of the class III genes, flgM, which encodes an anti-u factor that prevents UF activity unless the products of all the class II genes are expressed and functional (11).The flagellar regulon in B. subtilis is not as well characterized as that in the enterobacteria, but it appears to differ in several respects (5). Remarkably, most of the identified flagel...

Phosphorylation of the Response Regulator CheV Is Required for Adaptation to Attractants during Bacillus subtilisChemotaxis

“…CheV is a two-domain protein with an N-terminal CheW-like domain and a C-terminal two-component receiver domain (21). Earlier experiments showed that cheW and cheV null mutants had wild-type biases and were able to respond and adapt to large stepwise increase of the attractant azetidine-2-carboxylic acid (22).…”

Attractant Binding Induces Distinct Structural Changes to the Polar and Lateral Signaling Clusters in Bacillus subtilis Chemotaxis

“…CheV, a hybrid protein consisting of an N-terminal CheW-like domain and a C-terminal response regulator domain, is functionally redundant to CheW in B. subtilis; loss of either protein does not prevent adaptation but does lead to a minor reduction in chemotaxis efficiency (23,27). Loss of both proteins, however, completely abrogates chemotaxis.…”

“…This protein is functionally similar to CheW and is believed to function in a separate, methylationindependent adaptation system (23,26). First discovered and characterized in B. subtilis (23,27), CheV has subsequently been found in numerous other bacteria including Salmonella enterica but not E. coli (28 -31). Interestingly, in the gastric pathogen Helicobacter pylori, the single adaptation system employs three CheV paralogues but not reversible receptor methylation (24,32).…”

CheV1 Plays an Important Role in Chemotaxis of Vibrio Cholerae

“…The genome sequence also showed a similar set of proteins other than the core signal transduction proteins, namely CheV proteins, which are not present in E. coli but are reported in B. subtilis [14], [15], H. pylori [16], [17], S. enterica [18]. These CheV proteins are the fusion proteins consisting of a N-terminal CheW-like (adaptor-like) and a C-terminal CheY-like (response regulator-like) domains.…”