Multicopy suppression of a gacA mutation by the infC operon in Pseudomonas fluorescens CHA0: competition with the global translational regulator RsmA.
The gacA gene of the biocontrol strain Pseudomonas fluorescens CHA0 codes for a response regulator which, together with the sensor kinase GacS (=LemA), is required for the production of exoenzymes and secondary metabolites involved in biocontrol, including hydrogen cyanide (HCN). A gacA multicopy suppressor was isolated from a cosmid library of strain CHA0 and identified as the infC-rpmI-rplT operon, which encodes the translation initiation factor IF3 and the ribosomal proteins L35 and L20. The efficiency of suppression was about 30%, as determined by the use of a GacA-controlled reporter construct, i.e. a translational hcnA'-'lacZ fusion. Overexpression of the rsmA gene (coding for a global translational repressor) reversed the suppressive effect of the amplified infC operon. This finding suggests that some product(s) of the infC operon can compete with RsmA at the level of translation in P. fluorescens CHA0 and that important biocontrol traits can be regulated at this level.
Blumer
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Laboratoire de Biologie Microbienne, Université de Lausanne, CH-1015, Lausanne, Switzerland.
Haas
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D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D039621:Eukaryotic Initiation Factor-3; D005809:Genes, Regulator; D008969:Molecular Sequence Data; D009154:Mutation; D009876:Operon / Q000235:genetics*; D010448:Peptide Initiation Factors / Q000235:genetics* / Q000378:metabolism; D011551:Pseudomonas fluorescens / Q000235:genetics*; D016601:RNA-Binding Proteins; D011933:Reagent Kits, Diagnostic; D012097:Repressor Proteins / Q000235:genetics* / Q000378:metabolism; D013489:Suppression, Genetic
D001426:Bacterial Proteins; D039621:Eukaryotic Initiation Factor-3; C091100:GacA protein, Bacteria; D010448:Peptide Initiation Factors; D016601:RNA-Binding Proteins; D011933:Reagent Kits, Diagnostic; D012097:Repressor Proteins; C095468:RsmA protein, Erwinia carotovora