Structure and Function of the RedJ Protein, a Thioesterase from the Prodiginine Biosynthetic Pathway in Streptomyces coelicolor

摘要: Prodiginines are a class of red-pigmented natural products with immunosuppressant, anticancer, and antimalarial activities. Recent studies on prodiginine biosynthesis in Streptomyces coelicolor have elucidated the function many enzymes within pathway. However, RedJ, which was predicted to be an editing thioesterase based sequence similarity, is unknown. We report here genetic, biochemical, structural characterization redJ gene product. Deletion S. leads 75% decrease production, demonstrating its importance for biosynthesis. RedJ exhibits activity selectivity substrates having long acyl chains lacking β-carboxyl substituent. The has 1000-fold greater catalytic efficiency linked carrier protein (ACP) than corresponding CoA thioester substrates. Also, strongly discriminates against streptomycete ACP fatty acid preference RedQ, 2.12 A resolution crystal structure provides insights into molecular basis observed substrate selectivity. hydrophobic pocket active site chamber positioned bind chains, as suggested by long-chain ligand from crystallization solution bound this pocket. accessibility controlled position highly flexible entrance flap. These data combined previous support novel role facilitating transfer dodecanoyl chain one another en route key biosynthetic intermediate 2-undecylpyrrole.