Codon usage is involved in regulation antibiotic production in Pseudomonas protegens Pf-5
Q. YAN (1), B. Philmus (2), C. Hesse (3), J. Chang (2), J. Loper (4) (1) Oregon State University, U.S.A.; (2) Oregon State University, U.S.A.; (3) USDA-ARS Horticultural Crops Research Unit, U.S.A.; (4) USDA-ARS Horticultural Crops Research Laboratory, U.S.A.

Pseudomonas protegens Pf-5 colonizes seed and root surfaces, suppresses soilborne plant diseases, and produces at least seven antibiotics toxic to fungal plant pathogens. Complex regulatory circuits control antibiotic production and influence the reliability of biological control by Pf-5 and other bacterial antagonists. Biased codon usage has been proposed as a general mechanism for post-transcriptional regulation in bacteria and our bioinformatic analysis revealed that the six rarest codons of Pf-5 are present in all seven known antibiotic biosynthesis gene clusters. We focused on pltR, which encodes a key regulator of pyoluteorin (Plt) production.  A Pf-5 mutant in which 23 types of rare codons of pltR were substituted with synonymous preferred codons produced Plt at a level 15 times higher than the wild-type.  Substitution of AGA, which is the rarest codon in Pf-5, with a preferred Arg codon resulted in a variant of pltR that conferred increased Plt production and expression of plt genes. Furthermore, overexpression of tRNAArgUCU, the cognate tRNA for the AGA codon, significantly increased Plt production. Biased codon usage has been linked to the regulation of many phenotypes in eukaryotes and prokaryotes and influences antibiotic production by Streptomyces spp. To our knowledge, this is the first example of a rare codon regulating of antibiotic production by a Gram-negative bacterium.

Abstract Number: P3-82
Session Type: Poster