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Open Access Research article

Genome-wide transcriptome analysis reveals that a pleiotropic antibiotic regulator, AfsS, modulates nutritional stress response in Streptomyces coelicolor A3(2)

Wei Lian1, Karthik P Jayapal1, Salim Charaniya1, Sarika Mehra1, Frank Glod2, Yun-Seung Kyung1, David H Sherman2 and Wei-Shou Hu1*

Author Affiliations

1 Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Ave. SE., Minneapolis, MN 55455, USA

2 Life Sciences Institute, Departments of Medicinal Chemistry, Chemistry, Microbiology & Immunology, University of Michigan, 210 Washtenaw Ave., Ann Arbor, MI 48109, USA

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BMC Genomics 2008, 9:56  doi:10.1186/1471-2164-9-56

Published: 29 January 2008

Abstract

Background

A small "sigma-like" protein, AfsS, pleiotropically regulates antibiotic biosynthesis in Streptomyces coelicolor. Overexpression of afsS in S. coelicolor and certain related species causes antibiotic stimulatory effects in the host organism. Although recent studies have uncovered some of the upstream events activating this gene, the mechanisms through which this signal is relayed downstream leading to the eventual induction of antibiotic pathways remain unclear.

Results

In this study, we employed whole-genome DNA microarrays and quantitative PCRs to examine the transcriptome of an afsS disruption mutant that is completely deficient in the production of actinorhodin, a major S. coelicolor antibiotic. The production of undecylprodigiosin, another prominent antibiotic, was, however, perturbed only marginally in the mutant. Principal component analysis of temporal gene expression profiles identified two major gene classes each exhibiting a distinct coordinate differential expression pattern. Surprisingly, nearly 70% of the >117 differentially expressed genes were conspicuously associated with nutrient starvation response, particularly those of phosphate, nitrogen and sulfate. Furthermore, expression profiles of some transcriptional regulators including at least two sigma factors were perturbed in the mutant. In almost every case, the effect of afsS disruption was not observed until the onset of stationary phase.

Conclusion

Our data suggests a comprehensive role for S. coelicolor AfsS as a master regulator of both antibiotic synthesis and nutritional stress response, reminiscent of alternative sigma factors found in several bacteria.