Coronafacoyl phytotoxin biosynthesis and evolution in the common scab pathogen Streptomyces scabiei

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DOIResolve DOI: https://doi.org/10.1128/AEM.01169-17
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  1. National Research Council Canada. Aquatic and Crop Resource Development
FormatText
TypeArticle
Journal titleApplied and Environmental Microbiology
ISSN0099-2240
1098-5336
Volume83
Issue19
Article numbere01169-17
Pages# of pages: 15
Subjectbiosynthesis; coronafacoyl phytotoxin; coronatine; cytochrome P450; gene cluster; jasmonic acid; Pseudomonas syringae; Streptomyces scabiei; plant pathogens; signaling
Abstract
Coronafacoyl phytotoxins are an important family of plant toxins that are produced by several different phytopathogenic bacteria, including the gammaproteobacterium Pseudomonas syringae and the actinobacterium Streptomyces scabiei (formerly Streptomyces scabies). The phytotoxins consist of coronafacic acid (CFA) linked via an amide bond to different amino acids or amino acid derivatives. Previous work suggested that S. scabiei and P. syringae use distinct biosynthetic pathways for producing CFA, which is subsequently linked to its amino acid partner to form the complete phytotoxin. Here, we provide further evidence that the S. scabiei CFA biosynthetic pathway is novel by characterizing the role of CYP107AK1, a predicted cytochrome P450 that has no homologue in P. syringae. Deletion of the CYP107AK1 gene abolished production of coronafacoyl-isoleucine (CFA-Ile), the primary coronafacoyl phytotoxin produced by S. scabiei. Structural elucidation of accumulated biosynthetic intermediates in the ΔCYP107AK1 mutant indicated that CYP107AK1 is required for introducing the oxygen atom that ultimately forms the carbonyl group in the CFA backbone. The CYP107AK1 gene along with two additional genes involved in CFA-Ile biosynthesis in S. scabiei were found to be associated with putative CFA biosynthetic genes in other actinobacteria but not in other organisms. Analysis of the overall genetic content and organization of known and putative CFA biosynthetic gene clusters, together with phylogenetic analysis of the core biosynthetic genes, indicates that horizontal gene transfer has played an important role in the dissemination of the gene cluster and that rearrangement, insertion, and/or deletion events have likely contributed to the divergent biosynthetic evolution of coronafacoyl phytotoxins in bacteria.
Publication date
PublisherAmerican Society for Microbiology
LanguageEnglish
Peer reviewedYes
NPARC number23002681
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Record created2017-12-20
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