φEC2, a new generalized transducing phage of Erwinia chrysanthemi

Résibois, A.; Colet, M.; Faelen, Michel; Schoonejans, Eric; Toussaint, Ariane

doi:10.1016/0042-6822(84)90013-8

Cited by 129 publications

(74 citation statements)

References 23 publications

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“…Transduction with phage ⌽EC2 was performed as described by Resibois et al (1984). Marker exchange recombinations were obtained after growth in a low-phosphate-concentration medium as described by Roeder and Collmer (1985).…”

Section: Genetic Techniquesmentioning

confidence: 99%

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Characterization of the Erwinia chrysanthemi expI–expR locus directing the synthesis of two N‐acyl‐homoserine lactone signal molecules

Nasser

Bouillant

Salmond

et al. 1998

Molecular Microbiology

166

120

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SummaryThe plant pathogen Erwinia chrysanthemi produces three acyl-homoserine lactones (acyl-HSLs). One has been identified as N-(3-oxohexanoyl)-homoserine lactone (OHHL), and the two others were supposed to be N-(hexanoyl)-homoserine lactone (HHL) and N-(decanoyl)-homoserine lactone (DHL). The genes for a quorum-sensing signal generator (expI ) and a response regulator (expR ) were cloned. These genes are convergently transcribed and display high similarity to the expI-expR genes of Erwinia carotovora. ExpI is responsible for both OHHL and HHL production. Inactivation of expI had little effect on pectinase synthesis in E. chrysanthemi, as expression of only two of the pectate lyase genes, pelA and pelB, was decreased. E. chrysanthemi expR mutants still produced acyl-HSL and pectinases. However, gel shift and DNAse I footprinting experiments showed that the purified E. chrysanthemi ExpR protein binds specifically to the promoter regions of the five major pel genes. Addition of OHHL modified the ExpR-DNA bandshift profiles, indicating that ExpR interacts with OHHL and binds to DNA in different ways, depending on the OHHL concentration. Localization of the ExpR binding sites just upstream of promoter regions suggests that ExpR functions as an activator of pel expression in the presence of OHHL. The absence of a phenotype in expR mutants strongly suggests that at least an additional interchangeable ExpR homologue exists in E. chrysanthemi. Finally, transcription of expI ::uidA and expR ::uidA fusions is dependent on the population density, suggesting the existence of a quorum-sensing hierarchy in E. chrysanthemi. These results suggest that the expI-expR locus is part of a complex autoregulatory system that controls quorum sensing in E. chrysanthemi.

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Section: Genetic Techniquesmentioning

confidence: 99%

“…After removal Resibois et al (1984) a. Genotype symbols are according to Bachmann (1990). lmrT c indicates that the transport system encoded by the gene lmrT, which mediates the entry of lactose, melibiose and raffinose into the cells, is constitutively expressed.…”

Section: Thin-layer Chromatography Of Acyl-hslsmentioning

confidence: 99%

Characterization of the Erwinia chrysanthemi expI–expR locus directing the synthesis of two N‐acyl‐homoserine lactone signal molecules

Nasser

Bouillant

Salmond

et al. 1998

Molecular Microbiology

166

120

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“…Construction of strains was performed by transferring genes from one strain of D. dadantii to another by generalized transduction with phage wEC2 according to Resibois et al (1984).…”

Section: Methodsmentioning

confidence: 99%

Inactivation of pecS restores the virulence of mutants devoid of osmoregulated periplasmic glucans in the phytopathogenic bacterium Dickeya dadantii

2014

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Dickeya dadantii is a phytopathogenic enterobacterium that causes soft rot disease in a wide range of plant species. Maceration, an apparent symptom of the disease, is the result of the synthesis and secretion of a set of plant cell wall-degrading enzymes (PCWDEs), but many additional factors are required for full virulence. Among these, osmoregulated periplasmic glucans (OPGs) and the PecS transcriptional regulator are essential virulence factors. Several cellular functions are controlled by both OPGs and PecS. Strains devoid of OPGs display a pleiotropic phenotype including total loss of virulence, loss of motility and severe reduction in the synthesis of PCWDEs. PecS is one of the major regulators of virulence in D. dadantii, acting mainly as a repressor of various cellular functions including virulence, motility and synthesis of PCWDEs. The present study shows that inactivation of the pecS gene restored virulence in a D. dadantii strain devoid of OPGs, indicating that PecS cannot be de-repressed in strains devoid of OPGs.

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“…The bacterial strains of D. dadantii and Escherichia coli and the plasmids used in this study are listed in Table 1. The phage Phi-EC2 was used to transfer the uidA-Km fusions in the regulator mutants by generalized transduction (Resibois et al, 1984). Bacteria were grown in LB or in M63 medium (Miller, 1992) and, when required, the media were solidified with 15 g agar l 21 .…”

Section: Methodsmentioning

confidence: 99%

A family 3 glycosyl hydrolase of Dickeya dadantii 3937 is involved in the cleavage of aromatic glucosides

Charaoui-Boukerzaza

Hugouvieux‐Cotte‐Pattat

2013

Microbiology

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Dickeya dadantii is a phytopathogenic bacterium secreting a large array of plant-cell-walldegrading enzymes that participate in the infection and maceration of the host plant tissue. Sequencing of the D. dadantii 3937 genome predicted several genes encoding potential glycosidases. One of these genes, bgxA, encodes a protein classified in family 3 of glycosyl hydrolases. Inactivation of bgxA and the use of a gene fusion revealed that this gene is not essential for D. dadantii pathogenicity but that it is expressed during plant infection. The bgxA expression is induced in the presence of glycosidic or non-glycosidic aromatic compounds, notably ferulic acid, cinnamic acid, vanillic acid and salicin. The BgxA enzyme has a principal b-Dglucopyranosidase activity and a secondary b-D-xylopyranosidase activity (ratio 70 : 1). This enzyme activity is inhibited by different aromatic glycosides or phenolic compounds, in particular salicin, arbutin, ferulic acid and vanillic acid. Together, the induction effects and the enzyme inhibition suggest that BgxA is mostly involved in the cleavage of aromatic b-glucosides. There is evidence of functional redundancy in the D. dadantii b-glucoside assimilation pathway. In contrast to other b-glucoside assimilation systems, involving cytoplasmic phospho-b-glucosidases, the cleavage of aromatic glucosides in the periplasmic space by BgxA may avoid the release of a toxic phenolic aglycone into the cytoplasm while still allowing for catabolism of the glucose moiety. INTRODUCTIONb-Glucosidases (b-D-glucopyranoside glucohydrolases, E.C.3.2.1.21) are a heterogeneous group of enzymes, which hydrolyse glycosidic bonds to release non-reducing terminal glucosyl residues from glycosides and oligosaccharides. These enzymes catalyse the hydrolysis of cellobiose and various b-glucosides, the aglycone of which can be an aromatic compound (Ketudat Cairns & Esen, 2010). bGlucosidases are universally found in all domains of living organisms, archaea, eubacteria and eukaryotes. Most microbial b-glucosidases have been investigated in the soil and plant microflora and they have been considered as the ultimate enzymic step in the biological conversion of cellulose into glucose. However, other b-glucosidases preferentially hydrolyse aryl b-glucosides, such as arbutin and salicin (Faure et al., 1999). b-Glucosidases have been the focus of several studies because of their roles in a variety of biological processes, namely, the conversion of cellulose to glucose, the release of aromatic compounds from flavourless glucosidic precursors, the detoxification of cyanogenic glucosides, and the synthesis of useful b-glucosides (Bhatia et al., 2002;Ismail & Hayes, 2005;Ketudat-Cairns & Esen, 2010). The classic enzyme classification (EC) system groups together glycoside hydrolases according to their substrate specificity, for example, the bglucosidases all have the designation EC3.2.1.21. An alternative classification system has been developed for glycoside hydrolases, based on amino acid sequence and structural simila...

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φEC2, a new generalized transducing phage of Erwinia chrysanthemi

Cited by 129 publications

References 23 publications

Characterization of the Erwinia chrysanthemi expI–expR locus directing the synthesis of two N‐acyl‐homoserine lactone signal molecules

Characterization of the Erwinia chrysanthemi expI–expR locus directing the synthesis of two N‐acyl‐homoserine lactone signal molecules

Inactivation of pecS restores the virulence of mutants devoid of osmoregulated periplasmic glucans in the phytopathogenic bacterium Dickeya dadantii

A family 3 glycosyl hydrolase of Dickeya dadantii 3937 is involved in the cleavage of aromatic glucosides

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