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

Lian W, Jayapal KP, Charaniya S, Mehra S, Glod F, Kyung YS, Sherman DH, Hu WS - BMC Genomics (2008)

Bottom Line: Overexpression of afsS in S. coelicolor and certain related species causes antibiotic stimulatory effects in the host organism.In almost every case, the effect of afsS disruption was not observed until the onset of stationary phase.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.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Ave. SE., Minneapolis, MN 55455, USA. wei.lian@abbott.com

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.

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Related in: MedlinePlus

Growth and antibiotic synthesis kinetics of M145 and YSK4425. (a) Growth measured using optical density at 450 nm. (b) and (c) Spectrophotometric measurements of antibiotic titers for undecylprodigiosin and actinorhodin. Time profiles for M145 (○, solid blue line) and YSK4425 (△, dashed red line) are shown. The curves represent data from one of two reproducible experiments. (d) Photograph shows the dramatic difference in antibiotic synthesis between the M145 and YSK4425. Pictures are culture samples taken ~4 days after inoculation, indicating that the observed absence of actinorhodin synthesis was a genuine abolishment rather than a delay in synthesis.
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Figure 1: Growth and antibiotic synthesis kinetics of M145 and YSK4425. (a) Growth measured using optical density at 450 nm. (b) and (c) Spectrophotometric measurements of antibiotic titers for undecylprodigiosin and actinorhodin. Time profiles for M145 (○, solid blue line) and YSK4425 (△, dashed red line) are shown. The curves represent data from one of two reproducible experiments. (d) Photograph shows the dramatic difference in antibiotic synthesis between the M145 and YSK4425. Pictures are culture samples taken ~4 days after inoculation, indicating that the observed absence of actinorhodin synthesis was a genuine abolishment rather than a delay in synthesis.

Mentions: Figure 1a–c shows the time profiles of growth and antibiotic titers of M145 and YSK4425 measured during the course of a two-day liquid culture in R5- medium. Disruption of afsS did not significantly change the growth kinetics. However, synthesis profiles of two major pigmented antibiotics were altered in the mutant. The most significant change was observed for the polyketide antibiotic, actinorhodin, which normally accumulates to significant levels in M145 giving the culture a distinctive deep blue color. Production of this antibiotic was completely abolished in YSK4425 (Figure 1c and 1d). This finding is much more dramatic than earlier reports where synthesis of actinorhodin was observed in afsS deletion strains [19], albeit to a much lesser extent compared to wild-type. This difference was most likely due to our use of R5- medium [20] which does not contain any inorganic phosphate source. Significant actinorhodin accumulation was observed in YSK4425 cultures grown in phosphate containing R2YE medium. Inorganic phosphate depletion is an important trigger for antibiotic synthesis in S. coelicolor [21] and, as will be shown later, AfsS is a possible link between phosphate starvation response and actinorhodin synthesis. Another major antibiotic in S. coelicolor, a red-pigmented tripyrrole, undecylprodigiosin, accumulated to a slightly lower extent in YSK4425 mainly in stationary phase.


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

Lian W, Jayapal KP, Charaniya S, Mehra S, Glod F, Kyung YS, Sherman DH, Hu WS - BMC Genomics (2008)

Growth and antibiotic synthesis kinetics of M145 and YSK4425. (a) Growth measured using optical density at 450 nm. (b) and (c) Spectrophotometric measurements of antibiotic titers for undecylprodigiosin and actinorhodin. Time profiles for M145 (○, solid blue line) and YSK4425 (△, dashed red line) are shown. The curves represent data from one of two reproducible experiments. (d) Photograph shows the dramatic difference in antibiotic synthesis between the M145 and YSK4425. Pictures are culture samples taken ~4 days after inoculation, indicating that the observed absence of actinorhodin synthesis was a genuine abolishment rather than a delay in synthesis.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2267785&req=5

Figure 1: Growth and antibiotic synthesis kinetics of M145 and YSK4425. (a) Growth measured using optical density at 450 nm. (b) and (c) Spectrophotometric measurements of antibiotic titers for undecylprodigiosin and actinorhodin. Time profiles for M145 (○, solid blue line) and YSK4425 (△, dashed red line) are shown. The curves represent data from one of two reproducible experiments. (d) Photograph shows the dramatic difference in antibiotic synthesis between the M145 and YSK4425. Pictures are culture samples taken ~4 days after inoculation, indicating that the observed absence of actinorhodin synthesis was a genuine abolishment rather than a delay in synthesis.
Mentions: Figure 1a–c shows the time profiles of growth and antibiotic titers of M145 and YSK4425 measured during the course of a two-day liquid culture in R5- medium. Disruption of afsS did not significantly change the growth kinetics. However, synthesis profiles of two major pigmented antibiotics were altered in the mutant. The most significant change was observed for the polyketide antibiotic, actinorhodin, which normally accumulates to significant levels in M145 giving the culture a distinctive deep blue color. Production of this antibiotic was completely abolished in YSK4425 (Figure 1c and 1d). This finding is much more dramatic than earlier reports where synthesis of actinorhodin was observed in afsS deletion strains [19], albeit to a much lesser extent compared to wild-type. This difference was most likely due to our use of R5- medium [20] which does not contain any inorganic phosphate source. Significant actinorhodin accumulation was observed in YSK4425 cultures grown in phosphate containing R2YE medium. Inorganic phosphate depletion is an important trigger for antibiotic synthesis in S. coelicolor [21] and, as will be shown later, AfsS is a possible link between phosphate starvation response and actinorhodin synthesis. Another major antibiotic in S. coelicolor, a red-pigmented tripyrrole, undecylprodigiosin, accumulated to a slightly lower extent in YSK4425 mainly in stationary phase.

Bottom Line: Overexpression of afsS in S. coelicolor and certain related species causes antibiotic stimulatory effects in the host organism.In almost every case, the effect of afsS disruption was not observed until the onset of stationary phase.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.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Ave. SE., Minneapolis, MN 55455, USA. wei.lian@abbott.com

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.

Show MeSH
Related in: MedlinePlus