Relative roles of the fla/che P(A), P(D-3), and P(sigD) promoters in regulating motility and sigD expression in Bacillus subtilis.
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.
Department of Biology, San Francisco State University, San Francisco, California 94132, USA.
J T
JT
West
W
W
Estacio
L
L
Márquez-Magaña
D001412:Bacillus subtilis / Q000235:genetics* / Q000502:physiology; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D004269:DNA, Bacterial; D012321:DNA-Directed RNA Polymerases / Q000235:genetics*; D005408:Flagellin; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D009876:Operon; D011401:Promoter Regions, Genetic; D012808:Sigma Factor / Q000235:genetics*
D001426:Bacterial Proteins; D004269:DNA, Bacterial; C096721:FleB protein, Yersinia enterocolitica; D012808:Sigma Factor; D005408:Flagellin; C081775:RNA polymerase sigma 70; D012321:DNA-Directed RNA Polymerases