J Bacteriol 2000 Sep;182(17):4841-8

Relative roles of the fla/che P(A), P(D-3), and P(sigD) promoters in regulating motility and sigD expression in Bacillus subtilis.

West JT, Estacio W, Marquez-Magana L.

Department of Biology, San Francisco State University, San Francisco, California 94132, USA.

Three promoters have been identified as having potentially important regulatory roles in governing expression of the fla/che operon and of sigD, a gene that lies near the 3' end of the operon. Two of these promoters, fla/che P(A) and P(D-3), lie upstream of the >26-kb fla/che operon. The third promoter, P(sigD), lies within the operon, immediately upstream of sigD. fla/che P(A), transcribed by E sigma(A), lies >/=24 kb upstream of sigD and appears to be largely responsible for sigD expression. P(D-3), transcribed by E sigma(D), has been proposed to participate in an autoregulatory positive feedback loop. P(sigD), a minor sigma(A)-dependent promoter, has been implicated as essential for normal expression of the fla/che operon. We tested the proposed functions of these promoters in experiments that utilized strains that bear chromosomal deletions of fla/che P(A), P(D-3), or P(sigD). Our analysis of these strains indicates that fla/che P(A) is absolutely essential for motility, that P(D-3) does not function in positive feedback regulation of sigD expression, and that P(sigD) is not essential for normal fla/che expression. Further, our results suggest that an additional promoter(s) contributes to sigD expression.

PMID: 10940026 [PubMed - indexed for MEDLINE]

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Márquez-Magaña Lab.
Department of Biology
SFSU, 1600 Holloway Avenue, San Francisco, CA 94132