Transcription from two promoters and autoregulation contribute to the control of expression of the Salmonella typhimurium flagellar regulatory gene flgM.
The flgM gene product has been shown to be a negative regulator of flagellin transcription in Salmonella typhimurium (K. L. Gillen and K. T. Hughes, J. Bacteriol. 173:2301-2310, 6453-6459, 1991; K. Ohnishi, K. Kutsukake, H. Suzuki, and T. Iino, Mol. Microbiol. 6:3149-3157, 1992). Mud-lac fusions to the flgM gene were isolated and used to characterize the regulation of flgM gene expression. Transcription of the flgM gene was decreased more than 30-fold in strains with the flagellar master regulatory genes, flhC and flhD, deleted. A class 2 flagellar defect caused a slight increase of flgM gene transcription unless a wild-type copy of the flgM gene was present, in which case transcription was decreased threefold. A deletion in the gene for the alternative sigma factor sigma 28 (FliA) caused a fourfold decrease in flgM expression. Insertional inactivation of a gene upstream of the flgM gene (flgA) in a fliA mutant strain caused transcription of the flgM gene to be decreased to a basal level. Northern (RNA) blot analysis confirmed the presence of two transcripts through the flgM gene, one which initiates upstream of the flgM gene and a second which initiates upstream of the flgA gene.
Gillen
K L
KL
Department of Microbiology, University of Washington, Seattle 98195.
Hughes
K T
KT
D000483:Alleles; D001483:Base Sequence; D002874:Chromosome Mapping; D002876:Chromosomes, Bacterial; D017931:DNA Primers; D004251:DNA Transposable Elements; D005408:Flagellin / Q000096:biosynthesis* / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D005809:Genes, Regulator; D006706:Homeostasis; D008969:Molecular Sequence Data; D005810:Multigene Family; D016254:Mutagenesis, Insertional; D011401:Promoter Regions, Genetic; D014176:Protein Biosynthesis; D012329:RNA, Bacterial / Q000096:biosynthesis / Q000302:isolation & purification; D012333:RNA, Messenger / Q000096:biosynthesis / Q000302:isolation & purification; D012486:Salmonella typhimurium / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic
D017931:DNA Primers; D004251:DNA Transposable Elements; D012329:RNA, Bacterial; D012333:RNA, Messenger; D005408:Flagellin