Sensing structural intermediates in bacterial flagellar assembly by export of a negative regulator.
The ability of a regulatory protein to sense the integrity of the bacterial flagellar structure was investigated. In response to a defective hook-basal body complex, the anti-sigma 28 FlgM protein inhibits flagellin transcription. In cells with a functional hook-basal body complex, the flagellin genes are transcribed normally and the FlgM protein is expelled into the growth medium. In strains with a defective hook-basal body structure, FlgM is absent from the media. The presence of flagellin protein in the media is substantially reduced in strains carrying a FlgM-LacZ protein fusion, suggesting that the fusion is blocking the flagellar export apparatus. These results suggest that the FlgM protein assesses the integrity of the flagellar hook-basal body complex by itself being a substrate for export by the flagellar-specific export apparatus.
Hughes
K T
KT
Department of Microbiology, University of Washington, Seattle 98195.
Gillen
K L
KL
Semon
M J
MJ
Karlinsey
J E
JE
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D005407:Flagella / Q000378:metabolism / Q000648:ultrastructure*; D005408:Flagellin / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D005809:Genes, Regulator; D008954:Models, Biological; D009024:Morphogenesis; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012486:Salmonella typhimurium / Q000235:genetics / Q000254:growth & development / Q000378:metabolism / Q000648:ultrastructure*; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic
D001426:Bacterial Proteins; C064971:FliA protein, Bacteria; D011993:Recombinant Fusion Proteins; D012808:Sigma Factor; C035832:hook protein, bacterial flagellum; D005408:Flagellin; C071266:FlgM protein, Bacteria