Abstract
Pseudomonas fluorescens WH6 produces the non-proteinogenic amino acid 4-formylaminooxyvinylglycine (FVG), a secondary metabolite with antibacterial and pre-emergent herbicidal activities. The gvg operon necessary for FVG production encodes eight required genes: one regulatory (gvgR), two of unknown functional potential (gvgA and C), three with putative biosynthetic function (gvgF, H, and I), and two small ORFs (gvgB and G). To gain insight into the role of GvgA and C in FVG production, we compared the transcriptome of knockout (KO) mutants of gvgR, A, and C to wild type (WT) to test two hypotheses: (1) GvgA and GvgC play a regulatory role in FVG production and (2) non-gvg cluster genes are regulated by GvgA and GvgC. Our analyses show that, collectively, 687 genes, including the gvg operon, are differentially expressed in all KO strains versus WT, representing >10% of the genome. Fifty-one percent of these genes were similarly regulated in all KO strains with GvgC having the greatest number of uniquely regulated genes. Additional transcriptome data suggest cluster regulation through feedback of a cluster product. We also discovered that FVG biosynthesis is regulated by L-glu, L-asp, L-gln, and L-asn and that resources are reallocated in KO strains to increase phenotypes involved in rhizocompetence including motility, biofilm formation, and denitrification. Altogether, differential transcriptome analyses of mutants suggest that regulation of the cluster is multifaceted and the absence of FVG production or its downregulation can dramatically shift the lifestyle of WH6.
Highlights
Pseudomonas spp. are well known for their ability to produce secondary metabolites (SM) with broad ranges of activities [1]
Given the dichotomy of plant growth promotion by an organism that produces an herbicidal compound, we are presented with a unique system in which to study the regulation, production, and potentially diverse ecological function of this secondary metabolite
We found that gvg- and many non-gvg cluster genes are differentially regulated in ∆gvgR, A, and C strains compared to wild type (WT)
Summary
Pseudomonas spp. are well known for their ability to produce secondary metabolites (SM) with broad ranges of activities [1]. The P. fluorescens group, frequently isolated from soil and the rhizosphere, produces an array of compounds that contribute to disease suppression and plant growth promotion [2]. Some of these compounds have been adopted for use in human health and many are being explored as possible next-generation pesticides. Pf WH6 produces a non-proteinogenic amino acid analog, 4-formylaminooxyvinylglycine (FVG), with an unusual internal aminooxy bond (Figure 1A, [6]) This compound has both antibacterial and pre-emergent herbicidal activity against weedy grasses [5,7,8]. Given the dichotomy of plant growth promotion by an organism that produces an herbicidal compound, we are presented with a unique system in which to study the regulation, production, and potentially diverse ecological function of this secondary metabolite
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
