Nutrient salvaging and metabolism by the intracellular pathogen Legionella pneumophila.

The Gram-negative bacterium Legionella pneumophila is ubiquitous in freshwater environments as a free-swimming organism, resident of biofilms, or parasite of protozoa. If the bacterium is aerosolized and inhaled by a susceptible human host, it can infect alveolar macrophages and cause a severe pneumonia known as Legionnaires' disease. A sophisticated cell differentiation program equips L.

The phtC-phtD locus equips Legionella pneumophila for thymidine salvage and replication in macrophages.

The phagosomal transporter (Pht) family of the major facilitator superfamily (MFS) is encoded by phylogenetically related intracellular gammaproteobacteria, including the opportunistic pathogen Legionella pneumophila. The location of the pht genes between the putative thymidine kinase (tdk) and phosphopentomutase (deoB) genes suggested that the phtC and phtD loci contribute to thymidine salvage in L. pneumophila.

The ATP:Co(I)rrinoid adenosyltransferase (CobA) enzyme of Salmonella enterica requires the 2'-OH group of ATP for function and yields inorganic triphosphate as its reaction byproduct.

The specificity of the ATP:corrinoid adenosyltransferase (CobA) enzyme of Salmonella enterica serovar Typhimurium LT2 for its nucleotide substrate was tested using ATP analogs and alternative nucleotide donors. The enzyme showed broad specificity for the nucleotide base and required the 2'-OH group of the ribosyl moiety of ATP for activity. (31)P NMR spectroscopy was used to identify inorganic triphosphate (PPP(i)) as the byproduct of the reaction catalyzed by the CobA enzyme.