Self-control of the PHO regulon: the PhoP-dependent protein PhoU controls negatively expression of genes of PHO regulon in Streptomyces coelicolor

Abstract

Phosphate control of the biosynthesis of secondary metabolites in Streptomyces is mediated by the two component system PhoR-PhoP. Linked to the phoR-phoP cluster, and expressed in the opposite orientation, is a phoU-like encoding gene with low identity to the phoU gene of Escherichia coli. Expression of this phoU-like gene is strictly dependent on PhoP activation. We have isolated a PhoU-null mutant and used transcriptomic and RNA-sequencing (RNA-seq) procedures to identify its transcription start site and regulation. RNA-seq studies identified two transcription start sites, one upstream of phoU and the second upstream of the mptA gene. Whereas transcription of PhoU is entirely dependent on PhoP, expression of the downstream mtpA gene is only partially dependent on PhoP activation. The phoU mutant grows more slowly than the parental strain, sporulates poorly and the spores lack pigmentation. Production of actinorhodin and undecylprodigiosin decreased in the phoU mutant, indicating that PhoU has a positive modulating effect on production of these antibiotics. Indeed, transcriptional studies of expression of the actII-ORF4 and redD genes indicated that the PhoU protein activates expression of these antibiotic regulators. Using the glpQ1 promoter as in vivo reporter of the activity of the PHO regulon genes, we observed that expression of glpQ1 is negatively modulated by PhoU. These results were confirmed by reverse transcription-PCR studies of three genes of the PHO regulon; that is, glpQ1, pstS and phoR. In conclusion, PhoU acts as a negative modulator of expression of the PHO regulon genes and as phoU expression is strictly dependent on PhoP activation, this mechanism appears to work as a feed-back control mechanism (self-regulation).The Journal of Antibiotics advance online publication, 1 November 2017; doi:10.1038/ja.2017.130.

The Balance Metabolism Safety Net: Integration of Stress Signals by Interacting Transcriptional Factors in Streptomyces and Related Actinobacteria

“…The pstSCAB operon was expressed as a transcriptional unit in A. mediterranei (Zhang et al, 2018) as reported also in S. coelicolor (Esteban et al, 2008) and confirmed by RNAseq studies (Martín-Martín et al, 2019). Nitrate has a well-known stimulatory effect on rifamycin biosynthesis by A. mediterranei.…”

Expression of genes of the Pho regulon is altered in Streptomyces coelicolor

“…However, since the causes of the low expression of PhoR/PhoP in SC remain to be clarified further investigation would be needed to confirm this hypothesis. Little is known on the regulation of PhoR/PhoP expression in Streptomyces besides that PhoP auto-controls positively the expression of the phoR/phoP operon from a promoter located upstream of phoR 43 while the PhoU regulator plays a negative role in the regulation of this operon 99 . phoP is also expressed from its own promoter located at the end of phoR 43 but very little is known concerning the control of phoP expression from this promoter.…”

Enzyme-Constrained Models and Omics Analysis of Streptomyces coelicolor Reveal Metabolic Changes that Enhance Heterologous Production

“…The response to phosphate depletion from the medium is achieved by a set of genes, positively regulated by PhoP, that are involved in phosphate scavenging, uptake, and saving ( Martin et al., 2012 ; Martin-Martin et al., 2018 ; Sola-Landa et al., 2003 ). In our cultivations the metabolic switch can be readily identified from the RNA-seq data by the rapid upregulation of this regulon after 35 h of cultivation in M145 ( Figure 2 C), thereby corroborating the model simulations ( Figure 2 D) and providing a more detailed picture of the underlying regulation.…”