Two transporters, TogT and TogMNAB, are responsible for oligogalacturonide uptake in Erwinia chrysanthemi 3937.
Erwinia chrysanthemi causes soft rot of plants by secreting pectinases which cleave pectin, a polysaccharide cementing the plant cell wall constituents. We demonstrated that two transporters mediate the uptake of the extracellularly formed oligomers in E. chrysanthemi. TogMNAB, a multicomponent transporter member of the ATP-binding cassette (ABC) superfamily, is only partially responsible for the uptake of pectic oligomers. Its action is completed by that of the second transporter, TogT, a member of the glycoside-pentoside-hexuronide (GPH) family (TC no. 2.2) which includes transporters involved in the uptake of complex sugars, mostly oligosaccharides and glycosides. Each transport system, TogMNAB and TogT, is able to independently mediate the transport of oligogalacturonides and the simultaneous inactivation of both is necessary to give a total absence of growth with pectin as the carbon source. The togT gene constitutes an independent transcriptional unit. Its expression is induced in the presence of pectic derivatives and it is subject to catabolite repression. In vitro, the repressor KdgR and the activator CRP both interact directly with the togT regulatory region. The decreased pathogenicity of single and double togT, togM mutants indicated that a deficiency in uptake of pectic oligomers leads to reduced bacterial multiplication which, in turn, limits plant maceration.
Hugouvieux-Cotte-Pattat
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Unité Microbiologie et Génétique--composante INSA, UMR UCB-INSA-CNRS 5122, Bat Louis Pasteur, INSA, 11 Avenue Jean Capelle, F-69621 Villeurbanne Cedex, France. cotte@insa-lyon.fr
Reverchon
S
S
D018528:ATP-Binding Cassette Transporters / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D001693:Biological Transport, Active; D002240:Carbohydrate Sequence; D002352:Carrier Proteins; D002373:Cyclic AMP Receptor Protein / Q000378:metabolism; D016974:Dickeya chrysanthemi / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D009004:Monosaccharide Transport Proteins / Q000235:genetics* / Q000378:metabolism*; D009154:Mutation; D009844:Oligosaccharides / Q000378:metabolism*; D010368:Pectins / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism; D014157:Transcription Factors; D014158:Transcription, Genetic
D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins; D002352:Carrier Proteins; D002373:Cyclic AMP Receptor Protein; C098628:KdgR protein, Erwinia chrysanthemi; D009004:Monosaccharide Transport Proteins; D009844:Oligosaccharides; D012097:Repressor Proteins; C446310:TogA protein, Erwinia chrysanthemi; C446311:TogB protein, Erwinia chrysanthemi; C446308:TogM protein, Erwinia chrysanthemi; C446309:TogN protein, Erwinia chrysanthemi; C446312:TogT protein, Erwinia chrysanthemi; D014157:Transcription Factors; D010368:Pectins