Studies of sigma D-dependent functions in Bacillus subtilis.
Gene expression in Bacillus subtilis can be controlled by alternative forms of RNA polymerase programmed by distinct sigma factors. One such factor, sigma D (sigma 28), is expressed during vegetative growth and has been implicated in the transcription of a regulon of genes expressed during exponential growth and the early stationary phase. We have studied several functions related to flagellar synthesis and chemotaxis in B. subtilis strains in which sigma D is missing or is present at reduced levels. Previous studies showed that a null mutant, which contains a disrupted copy of the sigma D structural gene (sigD), fails to synthesize flagellin and grows as long filaments. We now show that these defects are accompanied by the lack of synthesis of the methyl-accepting chemotaxis proteins and a substantial decrease in two autolysin activities implicated in cell separation. A strain containing an insertion upstream of the sigD gene that reduces the level of sigma D protein grew as short chains and was flagellated but was impaired in chemotaxis and/or motility. This reduced level of sigma D expression suggests that the sigD gene may be part of an operon. A strain containing an insertion downstream of the sigD gene expressed nearly wild-type levels of sigma D protein but was also impaired in chemotaxis and/or motility, suggesting that genes downstream of sigD may also be involved in these functions. Genetic experiments demonstrate that sigD is allelic to the flaB locus, which was initially isolated as a locus affecting flagellin expression (G. F. Grant and M. I. Simon, J. Bacteriol. 99:116-124, 1969).
Márquez
L M
LM
Department of Biochemistry, University of California, Berkeley 94720.
Helmann
J D
JD
Ferrari
E
E
Parker
H M
HM
Ordal
G W
GW
Chamberlin
M J
MJ
D000483:Alleles; D001329:Autolysis; D001412:Bacillus subtilis / Q000235:genetics / Q000502:physiology*; D001426:Bacterial Proteins; D002633:Chemotaxis; D005408:Flagellin / Q000032:analysis / Q000235:genetics; D008565:Membrane Proteins / Q000032:analysis; D000072236:Methyl-Accepting Chemotaxis Proteins; D009068:Movement; D009154:Mutation; D012808:Sigma Factor / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D014157:Transcription Factors / Q000502:physiology*
D001426:Bacterial Proteins; D008565:Membrane Proteins; D000072236:Methyl-Accepting Chemotaxis Proteins; D012808:Sigma Factor; D014157:Transcription Factors; D005408:Flagellin