Specialized Metabolites from Ribosome Engineered Strains of Streptomyces clavuligerus.

Arshad Ali Shaikh,Kapil Tahlan,Santosh K Srivastava,Louis-Felix Nothias,Pieter C Dorrestein

doi:10.3390/metabo11040239

Abstract

Bacterial specialized metabolites are of immense importance because of their medicinal, industrial, and agricultural applications. Streptomyces clavuligerus is a known producer of such compounds; however, much of its metabolic potential remains unknown, as many associated biosynthetic gene clusters are silent or expressed at low levels. The overexpression of ribosome recycling factor (frr) and ribosome engineering (induced rpsL mutations) in other Streptomyces spp. has been reported to increase the production of known specialized metabolites. Therefore, we used an overexpression strategy in combination with untargeted metabolomics, molecular networking, and in silico analysis to annotate 28 metabolites in the current study, which have not been reported previously in S. clavuligerus. Many of the newly described metabolites are commonly found in plants, further alluding to the ability of S. clavuligerus to produce such compounds under specific conditions. In addition, the manipulation of frr and rpsL led to different metabolite production profiles in most cases. Known and putative gene clusters associated with the production of the observed compounds are also discussed. This work suggests that the combination of traditional strain engineering and recently developed metabolomics technologies together can provide rapid and cost-effective strategies to further speed up the discovery of novel natural products.

Highlights

Streptomyces are Gram-positive filamentous bacteria that undergo sporulation and comprise the largest genus of the phylum Actinobacteria [1]
A total of 5786 spectral features were detected during the analysis, some of which were only present in extracts from S. clavuligerus strains overexpressing either frr, rpsL, or rpsL variants (Figure 1)
The number of spectral features detected in the positive ionization mode in extracts from S. clavuligerus strains overexpressing any individual rpsL variant was greater than those overexpressing frr or rpsL (Figure 1), suggesting metabolic modulation due to ribosomal protein S12 modification

Summary

Introduction

Streptomyces are Gram-positive filamentous bacteria that undergo sporulation and comprise the largest genus of the phylum Actinobacteria [1]. They are found in various natural environments, such as soil and marine sediments. Streptomyces genomes range from 5 to 12.5 Mbp in size and contain an average of 39 biosynthetic gene clusters (BGCs) [2], responsible for the production of numerous and diverse specialized (or secondary) metabolites (SMs), many of which are used in medicine, industry, and agriculture [1,2]. Streptomyces clavuligerus is the industrial producer of clavulanic acid, a β-lactamase inhibitor used in combination with β-lactam antibiotics to treat certain otherwise-resistant bacterial infections [3]. Different genome sequencing studies have reported the presence of 49–58 SM

Methods

Results

Conclusion