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The Salmonella Spi1 virulence regulatory protein HilD directly activates transcription of the flagellar master operon flhDC

  • Singer, Hanna M. Microbiologie, Département de Médecine, Université de Fribourg, Switzerland
  • Kühne, Caroline Helmholtz Centre for Infection Research, Braunschweig, Germany
  • Deditius, Julia A. Helmholtz Centre for Infection Research, Braunschweig, Germany
  • Hughes, Kelly T. Department of Biology, University of Utah, Salt Lake City, USA
  • Erhardt, Marc Microbiologie, Département de Médecine, Université de Fribourg, Switzerland - Helmholtz Centre for Infection Research, Braunschweig, Germany
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    04.01.2014
Published in:
  • Journal of Bacteriology. - 2014, vol. 196, no. 7, p. 1448–1457
English Infection of intestinal epithelial cells is dependent on the Salmonella enterica serovar Typhimurium pathogenicity island 1 (Spi1)-encoded type III injectisome system and flagellar motility. Thus, the expression of virulence and flagellar genes is subject to tight regulatory control mechanisms in order to ensure the correct spatiotemporal production of the respective gene products. In this work, we reveal a new level of cross-regulation between the Spi1 and flagellar regulatory systems. Transposon mutagenesis identified a class of mutants that prevented flhDC autorepression by overexpressing HilD. HilD, HilC, RtsA, and HilA comprise a positive regulatory circuit for the expression of the Spi1 genes. Here, we report a novel transcriptional cross talk between the Spi1 and flagellar regulons where HilD transcriptionally activates flhDC gene expression by binding to nucleotides −68 to −24 upstream from the P5 transcriptional start site. We additionally show that, in contrast to the results of a previous report, HilA does not affect flagellar gene expression. Finally, we discuss a model of the cross-regulation network between Spi1 and the flagellar system and propose a regulatory mechanism via the Spi1 master regulator HilD that would prime flagellar genes for rapid reactivation during host infection.
Faculty
Faculté des sciences et de médecine
Department
Département de Médecine
Language
  • English
Classification
Biology
License
License undefined
Identifiers
Persistent URL
https://folia.unifr.ch/unifr/documents/303641
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