ePrints

Complex transcriptional control of the antibiotic regulator afsS in Streptomyces: PhoP and AfsR are overlapping, competitive activators

Lookup NU author(s): Dr Fernando Santos Beneit

Downloads

Full text for this publication is not currently held within this repository. Alternative links are provided below where available.

Abstract

The afsS gene of several Streptomyces species encodes a small sigma factor-like protein that acts as an activator of several pathway-specific regulatory genes (e.g., actII-ORF4 and redD in Streptomyces coelicolor). The two pleiotropic regulators AfsR and PhoP bind to overlapping sequences in the -35 region of the afsS promoter and control its expression. Using mutated afsS promoters containing specific point mutations in the AfsR and PhoP binding sequences, we proved that the overlapping recognition sequences for AfsR and PhoP are displaced by 1 nucleotide. Different nucleotide positions are important for binding of AfsR or PhoP, as shown by electrophoretic mobility shift assays and by reporter studies using the luxAB gene coupled to the different promoters. Mutant promoter M5 (with a nucleotide change at position 5 of the consensus box) binds AfsR but not PhoP with high affinity (named "superAfsR"). Expression of the afsS gene from this promoter led to overproduction of actinorhodin. Mutant promoter M16 binds PhoP with extremely high affinity ("superPhoP"). Studies with ΔafsR and ΔphoP mutants (lacking AfsR and PhoP, respectively) showed that both global regulators are competitive transcriptional activators of afsS. AfsR has greater influence on expression of afsS than PhoP, as shown by reverse transcriptase PCR (RT-PCR) and promoter reporter (luciferase) studies. These two high-level regulators appear to integrate different nutritional signals (particularly phosphate limitation sensed by PhoR), S-adenosylmethionine, and other still unknown environmental signals (leading to AfsR phosphorylation) for the AfsS-mediated control of biosynthesis of secondary metabolites

Publication metadata

Author(s): Santos-Beneit F, Rodríguez-García A, Martín JF

Publication type: Article

Publication status: Published

Journal: Journal of Bacteriology

Year: 2011

Volume: 193

Pages: 2242-2251

Print publication date: 04/03/2011

ISSN (print): 0021-9193

ISSN (electronic): 1098-5530

Publisher: American Society for Microbiology

URL: http://dx.doi.org/10.1128/JB.01462-10

DOI: 10.1128/JB.01462-10

PubMed id: 21378195

Altmetrics

Share