Production of a Novel Amide‐Containing Polyene by Activating a Cryptic Biosynthetic Gene Cluster in Streptomyces sp. MSC090213JE08

Abstract

Streptomyces sp. MSC090213JE08 seems to have more than 20 cryptic biosynthetic gene clusters for secondary metabolites. We aimed to activate some of them by forced production of Streptomyces antibiotic regulatory protein (SARP) family transcriptional activators. We constructed seven recombinant strains, each of which contained a SARP gene under the control of a constitutive promoter, and subjected them to comparative metabolic profiling analysis. Four of the seven strains produced nine metabolites that were hardly detected in the control strains. We isolated a new metabolite (named ishigamide) from the SARP-7-expressing strain and determined its structure as 3-((2E,4E,6E,8E)-13-hydroxytetradeca-2,4,6,8-tetraenamido)propanoic acid. Genome scanning and gene disruption studies identified the ishigamide biosynthetic gene cluster adjacent to the SARP-7 gene. We think that a new subfamily of type II polyketide synthase is involved in the biosynthesis of the polyene structure of ishigamide.

Reconstitution of a Type II Polyketide Synthase that Catalyzes Polyene Formation

“…Examples are IgaPKS in ishigamide biosynthesis (Scheme ) from Streptomyces sp. MSC090213JE08, Sky PKS in skyllamycin biosynthesis from Streptomyces sp. Acta 2897, and Sim/Smc PKS in simocyclinone biosynthesis from Streptomyces antibioticus and Kitasatospora sp.…”

“…IgaPKS was predicted to assemble the polyene portion of ishigamide through a repeating cycle of condensation, reduction, and dehydration, catalyzed by KS–CLF (Iga11–Iga12), KR (Iga13), and DH (Iga16), respectively (Scheme ) . The polyketide chain elongation occurs on ACP (Iga10).…”

Reconstitution of a Type II Polyketide Synthase that Catalyzes Polyene Formation

“…MSC090213JE08, [8] Sky PKS in skyllamycin biosynthesis from Streptomyces sp.A cta 2897, [9] and Sim/Smc PKS in simocyclinone biosynthesis from Streptomyces antibioticus and Kitasatospora sp.1 52608. [10] Interestingly,t hese type II PKSs are distributed only in actinobacteria ( Figure S3).…”

“…[8] The polyketide chain elongation occurs on ACP( Iga10). [8] The polyketide chain elongation occurs on ACP( Iga10).…”

“…IgaPKS was predicted to assemble the polyene portion of ishigamide through arepeating cycle of condensation, reduction, and dehydration, catalyzed by KS-CLF (Iga11-Iga12), KR (Iga13), and DH (Iga16), respectively (Scheme 1). [8] The polyketide chain elongation occurs on ACP( Iga10). To analyze the function of these Iga proteins,weobtained them as recombinant proteins ( Figure S4a, ba nd Figure S5).…”