Article
- The EMBO Journal (2005) 24, 2034 - 2042
- doi:10.1038/sj.emboj.7600668
Published online: 5 May 2005
Subject Categories:
Sensing wetness: a new role for the bacterial flagellum
Qingfeng Wang1, Asaka Suzuki1, Susana Mariconda1, Steffen Porwollik2 and Rasika M Harshey1
- Section of Molecular Genetics and Microbiology & Institute of Cellular and Molecular Biology, University of Texas at Austin, Austin, TX, USA
- Sidney Kimmel Cancer Center, San Diego, CA, USA
Correspondence to:
Rasika M Harshey, Section of Molecular Genetics and Microbiology & Institute of Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA. Tel.: +1 512 471 6881; Fax: +1 512 471 7088; E-mail: rasika@uts.cc.utexas.edu
Received 10 February 2005; Accepted 11 April 2005
Abstract
We have uncovered a new role for the bacterial flagellum in sensing external wetness. An investigation into why mutants in the chemotaxis signaling pathway of Salmonella typhimurium exhibit fewer and shorter flagella than wild-type when propagated on a surface, first showed that the mutants downregulate only a small set of genes on swarm media—class 3 or 'late' motility genes, and genes associated with the pathogenicity island SPI-1 TTSS (type three secretion system). Based on observations that swarm colonies of the mutants appear less hydrated, we tested a model in which the flagellum itself is a sensor: suboptimal external hydration interferes with secretion of flagellin subunits, inhibiting filament growth and blocking normal export of the class 3 transcription inhibitor FlgM. We provide strong experimental support for the model. In addition, the data show that the flagellar and SPI-1 TTSS are coupled via regulatory proteins. These studies implicate the flagellum, a bacterial organ for motility, in sensing the external environment to modulate not only its own biogenesis but other physiological functions as well.
Keywords:
- chemotaxis signaling pathway,
- flagella biogenesis,
- flagellum as sensor,
- Salmonella pathogenicity island,
- swarming motility
MORE ARTICLES LIKE THIS
These links to content published by NPG are automatically generated
REVIEWS
Drug discovery in the ubiquitin?proteasome system
Nature Reviews Drug Discovery Review (01 Jul 2006)
EMBO reports Review (01 Jun 2005)
Coordinating assembly of a bacterial macromolecular machine
Nature Reviews Microbiology Review (01 Jun 2008)
RESEARCH
Cytoplasmic flagellin activates caspase-1 and secretion of interleukin 1β via Ipaf
Nature Immunology Article (01 Jun 2006)
