The PecT repressor interacts with regulatory regions of pectate lyase genes in Erwinia chrysanthemi

Castillo, Arnaud; Nasser, William; Condemine, Guy; Reverchon, Sylvie

doi:10.1016/s0167-4781(98)00158-4

Cited by 14 publications

(12 citation statements)

References 32 publications

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“…Sequences are numbered from the transcriptional start point P1. The regions protected by CRP, KdgR, ExpR and H‐NS in DNase I footprinting experiments are indicated; the binding site of PecT on the pecT gene was defined by in vivo genetic footprinting and in vitro band shift experiments (Castillo et al , 1998). Restriction sites used to radiolabel the probes are indicated.…”

Section: Resultsmentioning

confidence: 99%

H‐NS‐dependent activation of pectate lyases synthesis in the phytopathogenic bacterium Erwinia chrysanthemi is mediated by the PecT repressor

Nasser¹,

Reverchon

2002

Molecular Microbiology

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SummaryProduction of the main virulence determinant pectate lyases (Pels) of the phytopathogenic bacterium Erwinia chrysanthemi is modulated by a complex regulatory network involving the repressor proteins KdgR, PecS and PecT and the activator systems Pir, ExpI-ExpR and CRP. Of these regulators, CRP and PecT are particularly important since the absence of CRP or a slight overproduction of PecT leads to a drastic reduction in synthesis of Pel species. Recently, it has been shown that production of Pel species is strongly reduced in an E. chrysanthemi hns mutant, suggesting an activator function of the nucleoid-associated protein H-NS in the expression of the pel genes. Here, we report that the reduced synthesis of Pel species in the hns mutant results from a negative control, exerted by H-NS, on the transcription of the regulatory gene pecT. This H-NS/PecT cascade regulation is one of the first elucidations of a positive effect of H-NS on target gene expression. Moreover, we found that H-NS also represses the expression of expI, expR and pel genes. H-NS control is the result of H-NS binding to extended regions within the pecT, expI, expR and pel genes. Investigation of the simultaneous binding of CRP, RNA polymerase (RNAP) and H-NS on the pelD gene revealed that these three proteins form a nucleoprotein complex. Together, these data indicate that, by exerting a negative control at multiple levels, H-NS plays a crucial role in the E. chrysanthemi pel regulatory network. IntroductionThe virulence of the Gram-negative plant pathogen Erwinia chrysanthemi and other soft rot Erwinia species

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Section: Resultsmentioning

confidence: 99%

H‐NS‐dependent activation of pectate lyases synthesis in the phytopathogenic bacterium Erwinia chrysanthemi is mediated by the PecT repressor

Nasser¹,

Reverchon

2002

Molecular Microbiology

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“…PecT is a LysR-type regulator and is a dimer in solution (67). Electrophoretic mobility shift assays demonstrated that two PecT dimers bind cooperatively to the regulatory regions of pectate lyase genes, although the binding affinity varies for different promoters (67).…”

Section: Vol 69 2005mentioning

confidence: 99%

“…Electrophoretic mobility shift assays demonstrated that two PecT dimers bind cooperatively to the regulatory regions of pectate lyase genes, although the binding affinity varies for different promoters (67). PecT also specifically interacts with the pecT regulatory region and represses its own synthesis (67,68). The nucleoid-associated protein H-NS plays a role in the negative control of pecT and also represses the expression of pel genes and of the QS system expI-expR (350).…”

Section: Vol 69 2005mentioning

confidence: 99%

Detection of and Response to Signals Involved in Host-Microbe Interactions by Plant-Associated Bacteria

Brencic

Winans

2005

Microbiol Mol Biol Rev

337

208

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Diverse interactions between hosts and microbes are initiated by the detection of host-released chemical signals. Detection of these signals leads to altered patterns of gene expression that culminate in specific and adaptive changes in bacterial physiology that are required for these associations. This concept was first demonstrated for the members of the family Rhizobiaceae and was later found to apply to many other plant-associated bacteria as well as to microbes that colonize human and animal hosts. The family Rhizobiaceae includes various genera of rhizobia as well as species of Agrobacterium. Rhizobia are symbionts of legumes, which fix nitrogen within root nodules, while Agrobacterium tumefaciens is a pathogen that causes crown gall tumors on a wide variety of plants. The plant-released signals that are recognized by these bacteria are low-molecular-weight, diffusible molecules and are detected by the bacteria through specific receptor proteins. Similar phenomena are observed with other plant pathogens, including Pseudomonas syringae, Ralstonia solanacearum, and Erwinia spp., although here the signals and signal receptors are not as well defined. In some cases, nutritional conditions such as iron limitation or the lack of nitrogen sources seem to provide a significant cue. While much has been learned about the process of host detection over the past 20 years, our knowledge is far from being complete. The complex nature of the plant-microbe interactions makes it extremely challenging to gain a comprehensive picture of host detection in natural environments, and thus many signals and signal recognition systems remain to be described

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“…Ten major regulators were identified (KdgR, PecS, PecT, CRP, H-NS, FIS, Fur, GacA, SlyA and MfbR) (Reverchon et al, 1991;1994;1997;Castillo et al, 1998;Franza et al, 2002;Nasser and Reverchon, 2002;Lebeau et al, 2008;Haque et al, 2009;Ouafa et al, 2012) and were reviewed in Charkowski and colleagues (2012). Most of these regulators control not only CWDE production but also other virulence factors such as exopolysaccharide production, motility and synthesis of compounds involved in resistance to oxidative burst (Castillo et al, 1998;Condemine et al, 1999;Reverchon et al, 2002;Hommais et al, 2008). The coordination of the expression of the pectinase genes has been mathematically modelled (Sepulchre et al, 2007;Kepseu et al, 2010b).…”

Section: Introductionmentioning

confidence: 99%

Vfm a new quorum sensing system controls the virulence of Dickeya dadantii

Nasser

Dorel

Wawrzyniak

et al. 2012

Environmental Microbiology

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135

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Dickeya dadantii is a plant pathogen that secretes cell wall-degrading enzymes (CWDE) that are responsible for soft-rot symptoms. Virulence genes are expressed in a concerted manner and culminate when bacterial multiplication slows. We identify a 25 kb vfm cluster required for D. dadantii CWDE production and pathogenesis. The vfm cluster encodes proteins displaying similarities both with enzymes involved in amino acid activation and with enzymes involved in fatty acid biosynthesis. These similarities suggest that the vfm genes direct the production of a metabolite. Cell-free supernatant from the D. dadantii wild-type strain restores CWDE production in vfm mutants. Collectively, our results indicate that vfm genes direct the synthesis of an extracellular signal and constitute a new quorum sensing system. Perception of the signal is achieved by the two-component system VfmH-VfmI, which activates the expression of the vfmE gene encoding an AraC regulator. VfmE then activates both the transcription of the CWDE genes and the expression of the vfm operons. The vfm gene cluster does not seem to be widespread among bacterial species but is conserved in other Dickeya species and could have been laterally transferred to Rahnella. This work highlights that entirely new families of bacterial languages remain to be discovered.

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The PecT repressor interacts with regulatory regions of pectate lyase genes in Erwinia chrysanthemi

Cited by 14 publications

References 32 publications

H‐NS‐dependent activation of pectate lyases synthesis in the phytopathogenic bacterium Erwinia chrysanthemi is mediated by the PecT repressor

H‐NS‐dependent activation of pectate lyases synthesis in the phytopathogenic bacterium Erwinia chrysanthemi is mediated by the PecT repressor

Detection of and Response to Signals Involved in Host-Microbe Interactions by Plant-Associated Bacteria

Vfm a new quorum sensing system controls the virulence of Dickeya dadantii

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