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United States Department of Agriculture

Agricultural Research Service

Title: Sequence Analysis and Transcriptional Regulation of the Pyoluteorin Biosynthetic Gene Cluster in Pseudomonas Fluorescens Pf-5

item Nowak-Thompson, B. - OREGON STATE UNIVERSITY
item Chaney, Nancy
item Loper, Joyce

Submitted to: International Congress on Pseudomonas Molecular Biology and Biotechnology
Publication Type: Proceedings
Publication Acceptance Date: June 1, 1997
Publication Date: N/A

Technical Abstract: Pyoluteorin is one of three antibiotics produced by Pseudomonas fluorescens Pf-5 in the rhizosphere. Nucleotide sequence analysis of a 24-kb genomic region required for pyoluteorin production has identified at least eight open reading frames (ORFs) that encode biosynthetic enzymes. The deduced gene products of the identified ORFs include a least two halogenases, a Type I polyketide synthase, a thioesterase, a dehydrogenase, and a peptide synthetase. The predicted amino acid sequences of the halogenases are similar to those of clorinating enzymes in the pyrrolnitrin and the chlortetracycline biosynthetic pathways. Multiple sequence alignments of the halogenase loci within the pyoluteorin gene cluster has identified an N-terminal peptide motif possessing the secondary structure necessary for NAD cofactor binding, suggesting that halogenases are a subclass of oxidoreductase enzymes. A presumed regulatory gene (pltR) also has been identified within the pyoluteorin gene cluster. The deduced pltR product exhibits similarity to several members of the LysR family of transcriptional regulators. PltR is essential for pyoluteorin production and is not required for the biosynthesis of other antifungal metabolites produced by Pf-5. Therefore, PltR appears to be a specific activator of the linked pyoluteorin biosynthetic genes and contrasts with the two-component regulatory system GacA/ApdA and the stationary-phase sigma factor RpoS,which influence the production of all three antifungal metabolites produced by Pf-5.

Last Modified: 4/21/2015
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