Bacillus subtilis cheR(B), which encodes the chemotactic methyltransferase, has been cloned and sequenced. CheR(B) is a polypeptide of 256 amino acids, with a predicted molecular mass of 28 kDa. A comparison of the predicted amino acid sequence of B. subtilis CheR(B) with that of Escherichia coli CheR(E) demonstrates that the two enzymes share 31% amino acid identity. The homology was functional in that the expression of cheB(B) in an E. coli cheR(E) null mutant made the bacteria Che+. In contrast to cheR(E) null mutants which show a strong smooth swimming bias, cheR(B) null mutants were predominantly tumbly. They respond to the addition and subsequent removal of attractant. They also respond to the addition of repellent but do not adapt; they resume prestimulus bias on removal of repellent. Tethering analysis of a culture of a cheR(B) null mutant revealed two distinct subpopulations, each demonstrating unique behaviors. One showed a strong clockwise flagellar rotation bias, whereas the other was more random. The latter phenotype may be due to a deficiency of CheB and may reflect an interaction of CheB and CheR. Measurements of CheB activity in the cheR null mutant showed them to be only 20% of wild type levels. We conclude from this work that CheR(B) functions to promote adaptation to repellent stimuli in B. subtilis, whereas CheR(E) functions to promote adaptation to attractant stimuli in E. coli.
|Original language||English (US)|
|Number of pages||7|
|Journal||Journal of Biological Chemistry|
|State||Published - 1993|
ASJC Scopus subject areas
- Molecular Biology
- Cell Biology