The biosynthetic gene cluster for the beta-lactam antibiotic tabtoxin in Pseudomonas syringae.

DNA sequence analysis revealed that the biosynthetic genes of the unusual beta-lactam antibiotic tabtoxin reside at the att site adjacent to the lysC tRNA gene in Pseudomonas syringae BR2. ORFs encoded within the region included ones with similarity to beta-lactam synthase and clavaminic acid synthase, as well as amino acid synthesis enzymes. Novel ORFs were present in a portion of the biosynthetic region associated with a toxin hypersensitivity phenotype.

Global regulation by gidA in Pseudomonas syringae.

Analysis of two virulence mutants of Pseudomonas syringae B728a revealed that the Tn 5 sites of insertion were within the gidA open reading frame (ORF). These mutations were pleiotropic, affecting diverse phenotypic traits, such as lipodepsipeptide (syringomycin and syringopeptin) antibiotic production, swarming, presence of fluorescent pigment, and virulence. Site-specific recombination of a disrupted gidA gene into the chromosome resulted in the same phenotypic pattern as transposon insertion.