Organization and characterization of a biosynthetic gene cluster for bafilomycin from Streptomyces griseus DSM 2608

Jae Hwang,Doo Nam,Hye Oh,Hyo Kim,Soo Kim

doi:10.1186/2191-0855-3-24

Abstract

Streptomyces griseus DSM 2608 produces bafilomycin, an antifungal plecomacrolide antibiotic. We cloned and sequenced an 87.4-kb region, including a polyketide synthase (PKS) region, methoxymalonate genes, flavensomycinate genes, and other putative regulatory genes. The 58.5kb of PKS region consisting 12 PKS modules arranged in five different PKS genes, was assumed to be responsible for the biosynthesis of plecomacrolide backbone including 16-membered macrocyclic lactone. All the modules showed high similarities with typical type I PKS genes. However, the starting module of PKS gene was confirmed to be specific for isobutyrate by sequence comparison of an acyltransferase domain. In downstream of PKS region, the genes for methoxymalonate biosynthesis were located, among which a gene for FkbH-like protein was assumed to play an important role in the production of methoxymalonyl-CoA from glyceryl-CoA. Further the genes encoding flavensomycinyl-ACP biosynthesis for the post-PKS tailoring were also found in the upstream of PKS region. By gene disruption experiments of a dehydratase domain of module 12 and an FkbH-like protein, this gene cluster was confirmed to be involved in the biosynthesis of bafilomycin.

Highlights

Plecomacrolide antibiotic is an unusual class of macrolide antibiotic which has a structural element of 6-membered hemiacetal ring connected to the macrolactone ring by C3-spacer (Dröse and Altendorf 1997)
Screening of a cosmid library of S. griseus genomic DNA As screening probes, the DNA fragments of KS, aminolevulinate synthase (ALS) and FkbH-like protein were firstly amplified from S. griseus DSM 2608 chromosomal DNA
Plecomacrolide antibiotic is an unusual macrolide antibiotic which has a structural element of 6-membered hemiacetal ring connected to the macrolactone ring

Summary

Introduction

Plecomacrolide antibiotic is an unusual class of macrolide antibiotic which has a structural element of 6-membered hemiacetal ring connected to the macrolactone ring by C3-spacer (Dröse and Altendorf 1997). Bowman et al (1988) reported that bafilomycin shows a high-affinity inhibitory function on vacuolar-type ATPase (V-ATPase), this compound became a widely-used biochemical research tool to study the function of this type of ATPases. This class of antibiotics makes a clear distinctive inhibition of V-ATPase activity from other type of ATPases (P-ATPase and F-ATPase), which can promote the accumulation of autophagic vacuoles and trigger Bax-dependent autophagy (Shacka et al 2006). This specific inhibitory function suggests the possibility of clinical application in the treatment of osteoporosis associated with excessive bone resorption (Farina and Gagliardi 2002; Xu et al 2007)

Methods

Results

Conclusion