Abstract
BackgroundAurantimycin (ATM), produced by Streptomyces aurantiacus JA 4570, is a potent antimicrobial and antitumor antibiotic. Although the chemical structure of ATM is highly distinctive and features a cyclohexadepsipeptide scaffold attached with a C14 acyl side chain, little is known about its biosynthetic pathway and regulatory mechanism.ResultsIn this work, we report the identification and characterization of the ATM biosynthetic gene cluster from S. aurantiacus JA 4570. Targeted inactivation of artG, coding for a NRPS enzyme, completely abolished ATM production, thereof demonstrating the target gene cluster (art) is responsible for ATM biosynthesis. Moreover, four NRPS adenylation (A) domains including a freestanding enzyme ArtC have been characterized in vitro, whose substrate specificities are consistent with in silico analysis. Further genetic analysis of the two regulatory genes artB and artX unambiguously suggested both of them play positive roles in ATM biosynthesis, and ATM-A production was thus rationally enhanced to about 2.5 fold via tandem overexpression of artB and artX in S. aurantiacus JA 4570.ConclusionsThese results will provide the basis for the understanding of precise mechanisms for ATM biosynthesis, and open the way for both rational construction of high-production ATM producer and orient-directed generation of designer ATM derivatives via synthetic biology strategies.Electronic supplementary materialThe online version of this article (doi:10.1186/s12934-016-0559-7) contains supplementary material, which is available to authorized users.
Highlights
Aurantimycin (ATM), produced by Streptomyces aurantiacus JA 4570, is a potent antimicrobial and antitumor antibiotic
Identification and analysis of the aurantimycins gene cluster ATM shares a similar cyclohexadepsipeptide scaffold to polyoxypeptin, whose biosynthetic pathway has been previously identified from Streptomyces sp
We utilized the nonribosomal peptide synthetases (NRPS) (PlyF, PlyG and PlyH) from polyoxypeptin pathway as individual probes to conduct the Blastp analysis against the genome of S. aurantiacus, which directly resulted in the identification of a continuous region in seq 14 (NZ_AOPZ01000014.1) involving homologs designated as ArtF (STRAU_0335, 55 % identity to PlyF), ArtG (STRAU_0336, 51 % identity to PlyG) and ArtH (STRAU_0337, 43 % identity to PlyG)
Summary
Aurantimycin (ATM), produced by Streptomyces aurantiacus JA 4570, is a potent antimicrobial and antitumor antibiotic. The chemical structure of ATM is highly distinctive and features a cyclohexadepsipeptide scaffold attached with a C14 acyl side chain, little is known about its biosynthetic pathway and regulatory mechanism. Further genetic analysis of the two regulatory genes artB and artX unambiguously suggested both of them play positive roles in ATM biosynthesis, and ATM-A production was rationally enhanced to about 2.5 fold via tandem overexpression of artB and artX in S. aurantiacus JA 4570. ATM features a 19 membered cyclohexadepsipeptide core scaffold attached by a C14 acyl side chain. Different ATM components share a distinctive structural feature with a tetrahydropyranyl-propionic acid acyl side chain linked to 2S, 3S-hydroxyleucine residue of the core scaffold via an exocyclic amide bond (Fig. 1) but differing in the extent of unsaturation of two opposite piperazic acid moieties. Despite the unique structure and diverse distribution of such moiety in natural products, the precise mechanism for its biosynthesis remained unknown and confused biochemists for
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