title: The effect of polyphosphate kinase gene deletion on polyhydroxyalkanoate accumulation and carbon metabolism in Pseudomonas putida KT2440.
abstract: The primary enzyme involved in polyphosphate (polyP) synthesis, polyP kinase (ppk), has been deleted in Pseudomonas putida KT2440. This has resulted in a threefold to sixfold reduction in polyhydroxyalkanoate (PHA) accumulation compared with the wild type under conditions of nitrogen limitation, with either temperature or oxidative (H2O2) stress, when grown on glucose. The accumulation of PHA by Δppk mutant was the same as the wild type under nitrogen-limiting growth conditions. There was no difference in polyP levels between wild-type and Δppk strains under all growth conditions tested. In the Δppk mutant proteome, polyP kinase (PPK) was undetectable, but up-regulation of the polyp-associated proteins polyP adenosine triphosphate (ATP)/nicotinamide adenine dinucleotide (NAD) kinase (PpnK), a putative polyP adenosine monophosphate (AMP) phosphotransferase (PP_1752), and exopolyphosphatase was observed. Δppk strain exhibited significantly retarded growth with glycerol as carbon and energy source (42 h of lag period compared with 24 h in wild-type strain) but similar growth to the wild-type strain with glucose. Analysis of gene transcription revealed downregulation of glycerol kinase and the glycerol facilitator respectively. Glycerol kinase protein expression was also downregulated in the Δppk mutant. The deletion of ppk did not affect motility but reduced biofilm formation. Thus, the knockout of the ppk gene has resulted in a number of phenotypic changes to the mutant without affecting polyP accumulation.
authors.affiliation: School of Biomedical and Biomolecular Science, University College Dublin, Belfield, Dublin, 4, Dublin, Ireland.
authors.forename: William T
authors.initials: WT
authors.lastname: Casey
authors.forename: Jasmina
authors.initials: J
authors.lastname: Nikodinovic-Runic
authors.forename: Pilar
authors.initials: P
authors.lastname: Fonseca Garcia
authors.forename: Maciej W
authors.initials: MW
authors.lastname: Guzik
authors.forename: John W
authors.initials: JW
authors.lastname: McGrath
authors.forename: John P
authors.initials: JP
authors.lastname: Quinn
authors.forename: Gerard
authors.initials: G
authors.lastname: Cagney
authors.forename: Maria Auxiliadora
authors.initials: MA
authors.lastname: Prieto
authors.forename: Kevin E
authors.initials: KE
authors.lastname: O'Connor
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism*; D002244:Carbon / Q000378:metabolism*; D017353:Gene Deletion; D005947:Glucose / Q000378:metabolism; D005990:Glycerol / Q000378:metabolism; D017856:Phosphotransferases (Phosphate Group Acceptor) / Q000235:genetics* / Q000378:metabolism*; D054813:Polyhydroxyalkanoates / Q000378:metabolism*; D016958:Pseudomonas putida / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D054813:Polyhydroxyalkanoates; D002244:Carbon; D017856:Phosphotransferases (Phosphate Group Acceptor); C022424:polyphosphate kinase; D005947:Glucose; D005990:Glycerol