Analysis of genes involved in biosynthesis of coronafacic acid, the polyketide component of the phytotoxin coronatine.
Coronafacic acid (CFA) is the polyketide component of coronatine (COR), a phytotoxin produced by the plant-pathogenic bacterium Pseudomonas syringae. The genes involved in CFA biosynthesis are encoded by a single transcript which encompasses 19 kb of the COR gene cluster. In the present study, the nucleotide sequence was determined for a 4-kb region located at the 3' end of the CFA biosynthetic gene cluster. Three open reading frames were identified and designated cfa8, cfa9, and tnp1; the predicted translation products of these genes showed relatedness to oxidoreductases, thioesterases, and transposases, respectively. The translational products of cfa8 and cfa9 were overproduced in Escherichia coli BL21; however, tnp1 was not translated in these experiments. Mutagenesis and complementation analysis indicated that cfa8 is required for the production of CFA and COR. Analysis of a cfa9 mutant indicated that this gene is dispensable for CFA and COR production but may increase the release of enzyme-bound products from the COR pathway; tnp1, however, had no obvious function in CFA or COR biosynthesis. A genetic strategy was used to produce CFA in a P. syringae strain which lacks the COR gene cluster; this approach will be useful in future studies designed to investigate biosynthetic products of the CFA gene cluster.
Rangaswamy
V
V
Department of Entomology and Plant Pathology, Oklahoma State University, Stillwater 74078-3032, USA.
Mitchell
R
R
Ullrich
M
M
Bender
C
C
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000737:chemistry / Q000378:metabolism*; D001427:Bacterial Toxins / Q000096:biosynthesis* / Q000737:chemistry; D001483:Base Sequence; D002874:Chromosome Mapping; D004926:Escherichia coli; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D007192:Indenes / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D005810:Multigene Family; D016296:Mutagenesis; D010088:Oxidoreductases / Q000096:biosynthesis / Q000235:genetics; D014176:Protein Biosynthesis; D011549:Pseudomonas / Q000235:genetics* / Q000378:metabolism; D011994:Recombinant Proteins / Q000096:biosynthesis; D013869:Thiolester Hydrolases / Q000096:biosynthesis / Q000235:genetics; D019895:Transposases / Q000096:biosynthesis / Q000235:genetics
D000596:Amino Acids; D001427:Bacterial Toxins; D007192:Indenes; D011994:Recombinant Proteins; C058487:coronatine; C084266:coronafacic acid; D010088:Oxidoreductases; D019895:Transposases; D013869:Thiolester Hydrolases