The Pho regulon: a huge regulatory network in bacteria

Abstract

One of the most important achievements of bacteria is its capability to adapt to the changing conditions of the environment. The competition for nutrients with other microorganisms, especially in the soil, where nutritional conditions are more variable, has led bacteria to evolve a plethora of mechanisms to rapidly fine-tune the requirements of the cell. One of the essential nutrients that are normally found in low concentrations in nature is inorganic phosphate (Pi). Bacteria, as well as other organisms, have developed several systems to cope for the scarcity of this nutrient. To date, the unique mechanism responding to Pi starvation known in detail is the Pho regulon, which is normally controlled by a two component system and constitutes one of the most sensible and efficient regulatory mechanisms in bacteria. Many new members of the Pho regulon have emerged in the last years in several bacteria; however, there are still many unknown questions regarding the activation and function of the whole system. This review describes the most important findings of the last three decades in relation to Pi regulation in bacteria, including: the PHO box, the Pi signaling pathway and the Pi starvation response. The role of the Pho regulon in nutritional regulation cross-talk, secondary metabolite production, and pathogenesis is discussed in detail.

Essential Genes Predicted in the Genome of Rubrivivax gelatinosus

“…However, phoU was categorized as essential in C. crescentus, B. subvibrioides, and R. palustris, suggesting this phenotype may be common (14,15,21). There is a growing link between Pho regulation and stress response, potentially by the action of ppGpp (31,33). The results of this and other TnSeq studies support the idea that the Pho regulon has larger impacts on cellular physiology than just regulating phosphate levels.…”

Draft Genomes Shed Light on the Dual Bacterial Symbiosis that Dominates the Microbiome of the Coral Reef Sponge Amphimedon queenslandica

“…We find a ppk gene in the genome of AqS1, suggesting that it could have the same capability, and supporting the hypothesis of Zhang et al (2015b) that oscillation between anoxic and oxic states inside sponges could select for polyP-accumulating organisms within the symbiotic community. In fact, AqS1 is well equipped for phosphorus metabolism, with the ability to detect environmental levels of inorganic phosphate and accordingly regulate its assimilation as necessary, using a phosphate regulon system (Santos-Beneit, 2015).…”

Comparative genomic, proteomic and exoproteomic analyses of three Pseudomonas strains reveals novel insights into the phosphorus scavenging capabilities of soil bacteria

“…These studies identified a number of genes/proteins involved in Pi scavenging underlining the importance of performing ‘omics’ to study Pi acquisition. In Pseudomonas , it has been shown that phosphate binding proteins (PBPs), APases, and virulence factors are associated with phosphate‐stress and regulated by PhoBR (Monds et al ., 2006; Bains et al ., 2012; Putker et al ., 2013: Santos‐Beneit, 2015). …”