Pip, a novel activator of phenazine biosynthesis in Pseudomonas chlororaphis PCL1391.
Secondary metabolites are important factors for interactions between bacteria and other organisms. Pseudomonas chlororaphis PCL1391 produces the antifungal secondary metabolite phenazine-1-carboxamide (PCN) that inhibits growth of Fusarium oxysporum f. sp. radius lycopersici the causative agent of tomato foot and root rot. Our previous work unraveled a cascade of genes regulating the PCN biosynthesis operon, phzABCDEFGH. Via a genetic screen, we identify in this study a novel TetR/AcrR regulator, named Pip (phenazine inducing protein), which is essential for PCN biosynthesis. A combination of a phenotypical characterization of a pip mutant, in trans complementation assays of various mutant strains, and electrophoretic mobility shift assays identified Pip as the fifth DNA-binding protein so far involved in regulation of PCN biosynthesis. In this regulatory pathway, Pip is positioned downstream of PsrA (Pseudomonas sigma factor regulator) and the stationary-phase sigma factor RpoS, while it is upstream of the quorum-sensing system PhzI/PhzR. These findings provide further evidence that the path leading to the expression of secondary metabolism gene clusters in Pseudomonas species is highly complex.
Girard
Geneviève
G
Leiden University, Institute of Biology, Clusius Laboratory, Wassenaarseweg 64, 2333 AL Leiden, The Netherlands.
Barends
Sharief
S
Rigali
Sébastien
S
van Rij
E Tjeerd
ET
Lugtenberg
Ben J J
BJ
Bloemberg
Guido V
GV
D000595:Amino Acid Sequence; D000935:Antifungal Agents / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000378:metabolism*; D005670:Fusarium / Q000187:drug effects / Q000254:growth & development; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D016680:Genome, Bacterial; D018551:Solanum lycopersicum / Q000382:microbiology; D008969:Molecular Sequence Data; D010619:Phenazines / Q000378:metabolism*; D010935:Plant Diseases / Q000382:microbiology; D018517:Plant Roots / Q000382:microbiology; D017354:Point Mutation; D011401:Promoter Regions, Genetic; D011549:Pseudomonas / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D016415:Sequence Alignment; D014158:Transcription, Genetic; D015854:Up-Regulation
D000935:Antifungal Agents; D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D010619:Phenazines; C420923:phenazine-1-carboxamide