Article

Temperature-dependent FlgM/FliA complex formation regulates Campylobacter jejuni flagella length.

Department of Infectious Diseases and Immunology, Utrecht University, Utrecht, the Netherlands.
Molecular Microbiology (impact factor: 5.01). 02/2010; 75(6):1577-91. DOI:10.1111/j.1365-2958.2010.07079.x pp.1577-91
Source: PubMed

ABSTRACT Regulation of the biosynthesis of the flagellar filament in bacteria containing multiple flagellin genes is not well understood. The major food-borne pathogen Campylobacter jejuni possesses on both poles a flagellum that consists of two different flagellin subunits, FlaA and FlaB. Here we identify the protein Cj1464 as a regulator of C. jejuni flagellin biosynthesis. The protein shares characteristics of the FlgM family of anti-sigma factor proteins: it represses transcription of sigma(28)-dependent genes, forms a complex with sigma factor FliA, and is secreted through the flagellar filament. However, unlike other FlgM proteins, the interaction of C. jejuni FlgM with FliA is regulated by temperature and the protein does not inhibit FliA activity during the formation of the hook-basal body complex (HBB). Instead, C. jejuni FlgM limits the length of the flagellar filament by suppressing the synthesis of both the sigma(28)- and the sigma(54)-dependent flagellins. The main function of the C. jejuni FlgM therefore is not to silence sigma(28)-dependent genes until the HBB is completed, but to prevent unlimited elongation of the flagellum, which otherwise leads to reduced bacterial motility.

0 0
 · 
0 Bookmarks
 · 
29 Views
  • Source
    Article: A protein thermometer controls temperature-dependent transcription of flagellar motility genes in Listeria monocytogenes.
    Heather D Kamp, Darren E Higgins
    [show abstract] [hide abstract]
    ABSTRACT: Facultative bacterial pathogens must adapt to multiple stimuli to persist in the environment or establish infection within a host. Temperature is often utilized as a signal to control expression of virulence genes necessary for infection or genes required for persistence in the environment. However, very little is known about the molecular mechanisms that allow bacteria to adapt and respond to temperature fluctuations. Listeria monocytogenes (Lm) is a food-borne, facultative intracellular pathogen that uses flagellar motility to survive in the extracellular environment and to enhance initial invasion of host cells during infection. Upon entering the host, Lm represses transcription of flagellar motility genes in response to mammalian physiological temperature (37°C) with a concomitant temperature-dependent up-regulation of virulence genes. We previously determined that down-regulation of flagellar motility is required for virulence and is governed by the reciprocal activities of the MogR transcriptional repressor and the bifunctional flagellar anti-repressor/glycosyltransferase, GmaR. In this study, we determined that GmaR is also a protein thermometer that controls temperature-dependent transcription of flagellar motility genes. Two-hybrid and gel mobility shift analyses indicated that the interaction between MogR and GmaR is temperature sensitive. Using circular dichroism and limited proteolysis, we determined that GmaR undergoes a temperature-dependent conformational change as temperature is elevated. Quantitative analysis of GmaR in Lm revealed that GmaR is degraded in the absence of MogR and at 37°C (when the MogR:GmaR complex is less stable). Since MogR represses transcription of all flagellar motility genes, including transcription of gmaR, changes in the stability of the MogR:GmaR anti-repression complex, due to conformational changes in GmaR, mediates repression or de-repression of flagellar motility genes in Lm. Thus, GmaR functions as a thermo-sensing anti-repressor that incorporates temperature signals into transcriptional control of flagellar motility. To our knowledge, this is the first example of a protein thermometer that functions as an anti-repressor to control a developmental process in bacteria.
    PLoS Pathogens 08/2011; 7(8):e1002153. · 9.13 Impact Factor
Data provided are for informational purposes only. Although carefully collected, accuracy cannot be guaranteed. The impact factor represents a rough estimation of the journal's impact factor and does not reflect the actual current impact factor. Publisher conditions are provided by RoMEO. Differing provisions from the publisher's actual policy or licence agreement may be applicable.

Keywords

anti-sigma factor proteins
 
bacterial motility
 
biosynthesis
 
C. jejuni flagellin biosynthesis
 
C. jejuni FlgM
 
different flagellin subunits
 
flagellum
 
HBB
 
hook-basal body complex
 
main function
 
major food-borne pathogen Campylobacter jejuni possesses
 
multiple flagellin genes
 
protein shares characteristics
 
regulator
 
secreted
 
sigma factor FliA
 
sigma(28)-dependent genes
 
sigma(54)-dependent flagellins
 
suppressing
 
unlimited elongation