title: Regulation of dinucleoside polyphosphate pools by the YgdP and ApaH hydrolases is essential for the ability of Salmonella enterica serovar typhimurium to invade cultured mammalian cells.
abstract: The ygdP and apaH genes of Salmonella enterica serovar Typhimurium (S. Typhimurium) encode two unrelated dinucleoside polyphosphate (NpnN) hydrolases. For example, YgdP cleaves diadenosine tetraphosphate (Ap4A) producing AMP and ATP, while ApaH cleaves Ap4A producing 2ADP. Disruption of ygdP, apaH individually, and disruption of both genes together reduced intracellular invasion of human HEp-2 epithelial cells by S. Typhimurium by 9-, 250-, and 3000-fold, respectively. Adhesion of the mutants was also greatly reduced compared with the wild type. Invasive capacity of both single mutants was restored by transcomplementation with the ygdP gene, suggesting that loss of invasion was due to increased intracellular NpnN. The normal level of 3 microM adenylated NpnN (ApnN) was increased 1.5-, 3.5-, and 10-fold in the ygdP, apaH and double mutants, respectively. Expression of the putative ptsP virulence gene downstream of ygdP was not affected in the ygdP mutant. Analysis of 19 metabolic enzyme activities and the ability to use a range of carbohydrate carbon sources revealed a number of differences between the mutants and wild type. The increase in intracellular NpnN in the mutants appears to cause changes in gene expression that limit the ability of S. Typhimurium to adhere to and invade mammalian cells.
authors.affiliation: School of Biological Sciences and Department of Medical Microbiology and Genito-urinary Medicine, University of Liverpool, Liverpool L69 7ZB, United Kingdom.
authors.forename: Thamir M
authors.initials: TM
authors.lastname: Ismail
authors.forename: C Anthony
authors.initials: CA
authors.lastname: Hart
authors.forename: Alexander G
authors.initials: AG
authors.lastname: McLennan
mesh_terms: D000249:Adenosine Monophosphate / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D001422:Bacterial Adhesion; D017173:Caenorhabditis elegans; D050260:Carbohydrate Metabolism; D002455:Cell Division; D003001:Cloning, Molecular; D015226:Dinucleoside Phosphates / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D005816:Genetic Complementation Test; D006801:Humans; D007700:Kinetics; D016296:Mutagenesis; D009154:Mutation; D009699:N-Glycosyl Hydrolases / Q000235:genetics / Q000502:physiology*; D010641:Phenotype; D010957:Plasmids / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012486:Salmonella typhimurium / Q000378:metabolism*; D014407:Tumor Cells, Cultured; D020298:U937 Cells
chemical_list: D015226:Dinucleoside Phosphates; D011994:Recombinant Proteins; D000249:Adenosine Monophosphate; C020733:diadenosine tetraphosphate; D000255:Adenosine Triphosphate; C477517:ApaH protein, Salmonella enterica; D009699:N-Glycosyl Hydrolases; C477516:YgdP protein, Salmonella enterica