Genes & Genetic Systems
Online ISSN : 1880-5779
Print ISSN : 1341-7568
ISSN-L : 1341-7568
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Two novel regulatory genes, fliT and fliZ, in the flagellar regulon of Salmonella
Kazuhiro KutsukakeTadayoshi IkebeShouji Yamamoto
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1999 Volume 74 Issue 6 Pages 287-292


The flagellar operons of Salmonella are divided into three classes with respect to their transcriptional hierarchy. Expression of the class 2 operons requires the class 1 gene products, FlhD and FlhC, and is increased by mutation in the flgM gene, which encodes a class 3-specific anti-sigma factor. Here we report the identification of two novel regulatory genes for class 2 transcription. Presence of the fliZ and fliT genes on multicopy plasmids enhanced and inhibited, respectively, transcription from a chromosomal class 2 promoter. Disruption of the fliZ and fliT genes on the chromosome decreased and increased, respectively, class 2 expression. These results suggest that the fliZ and fliT genes may encode positive and negative regulatory factors, respectively, for class 2 expression. Enhancement of class 2 expression by the flgM mutation was cancelled by the coexisting fliZ mutation, indicating that FliZ is essential for this enhancement.

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© 1999 by The Genetics Society of Japan
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