SEQUENCE, EXPRESSION AND TRANSCRIPTIONAL ANALYSIS OF THE CORONAFACATELIGASE-ENCODING GENE REQUIRED FOR CORONATINE BIOSYNTHESIS BY PSEUDOMONAS-SYRINGAE

Pseudomonas syringae pv. glycinea PG4180 produces the chlorosis-induci ng phytotoxin coronatine (COR), which consists of a polyketide compone nt, coronafacic acid (CFA), ligated by an amide bond to coronamic acid (CMA), an ethylcyclopropyl amino-acid derived from isoleucine. We rep ort the nucleotide sequence of a 2.37-kb region containing the coronaf acate ligase-encoding gene (cfl) which is required for the amide linka ge of CFA and CMA. The transcription start point for cfl was identifie d, and the Cfl protein was overproduced from the T7lac promoter in Esc herichia coli. The deduced amino-acid sequence of Cfl showed homology to a variety of adenylate-forming enzymes which bind and hydrolyze ATP in order to activate their substrates for further ligation.