title: Differential regulation of polyphosphate genes in Pseudomonas aeruginosa.
abstract: Phosphate homeostasis is tightly regulated in bacteria. Phosphate scarcity is overcome by inducing the expression of genes associated with the scavenging of phosphate and phosphate-containing molecules, while phosphate surplus is stored in the form of polyphosphate (polyP). Regulation of the genes involved in polyP metabolism was investigated. Knockout of the most distal gene of the pstSCAB-phoU operon that encodes a Pi-transport system results in large accumulation of polyphosphate (polyP). Here, we show that the phoU mutation differentially affects the transcription of ppk and ppx, that respectively, encode a polyP kinase and a polyP exopolyphosphatase, by increasing the former and reducing the latter, further contributing the accumulation of polyP. We also show that ppk forms an operon with the upstream gene hemB and that neither ppk nor ppx positively respond to Pi starvation. Furthermore, a putative PHO-box sequence in ppx regulatory region did not show a strong affinity for the PHO response regulator PhoB, while the promoter of hemB does not carry a PHO-box sequence. Altogether, the data indicate that the main genes involved in polyP metabolism, ppk and ppx, are differentially regulated in the absence of phoU, but neither gene belongs to the PHO regulon.
authors.affiliation: Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, SP, Brazil.
authors.forename: Nicolás Federico Villamil
authors.initials: NF
authors.lastname: Munévar
authors.affiliation: Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, SP, Brazil.
authors.forename: Luiz Gustavo
authors.initials: LG
authors.lastname: de Almeida
authors.affiliation: Departamento de Microbiologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, São Paulo, SP, Brazil. benys@usp.br.
authors.forename: Beny
authors.identifier: http://orcid.org/0000-0001-5394-9074
authors.initials: B
authors.lastname: Spira
mesh_terms: D015964:Gene Expression Regulation, Bacterial; D006159:Guanosine Tetraphosphate / Q000378:metabolism; D010749:Phosphoprotein Phosphatases / Q000235:genetics* / Q000378:metabolism; D017856:Phosphotransferases (Phosphate Group Acceptor) / Q000235:genetics* / Q000378:metabolism; D011122:Polyphosphates / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011550:Pseudomonas aeruginosa / Q000201:enzymology* / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic
chemical_list: D011122:Polyphosphates; D006159:Guanosine Tetraphosphate; D017856:Phosphotransferases (Phosphate Group Acceptor); C022424:polyphosphate kinase; D010749:Phosphoprotein Phosphatases; C080406:protein phosphatase 4
keywords: PHO regulon; Polyphosphate; Pseudomonas aeruginosa; ppk; ppx; pst