Open AccessA bacterial ecto‐triphosphate diphosphohydrolase similar to human CD39 is essential for intracellular multiplication of Legionella pneumophila
Author(s) -
Sansom Fiona M.,
Newton Hayley J.,
Crikis Sandra,
Cianciotto Nicholas P.,
Cowan Peter J.,
D'Apice Anthony J. F.,
Hartland Elizabeth L.
Publication year - 2007
Publication title -
cellular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.542
H-Index - 138
eISSN - 1462-5822
pISSN - 1462-5814
DOI - 10.1111/j.1462-5822.2007.00924.x
Subject(s) - biology , legionella pneumophila , nucleoside triphosphate , apyrase , microbiology and biotechnology , mutant , virulence , biochemistry , extracellular , nucleotide , gene , bacteria , genetics
Summary As part of its pathogenesis, Legionella pneumophila persists within human alveolar macrophages in non‐acidified organelles that do not mature into phagolysosomes. Two L. pneumophila genes, lpg0971 and lpg1905 , are predicted to encode ecto‐nucleoside triphosphate diphosphohydrolases (ecto‐NTPDases) that share sequence similarity with human CD39/NTPDase1. The predicted products possess five apyrase conserved domains that are typical of eukaryotic ecto‐NTPDases. In this study, we found that an lpg1905 mutant was recovered in lower numbers from macrophages, alveolar epithelial cells and the amoeba, Hartmannella vermiformis compared with wild‐type L. pneumophila and an lpg0971 mutant. Similar to human CD39, recombinant purified Lpg1905 exhibited ATPase and ADPase activity and possessed the ability to inhibit platelet aggregation. Mutation of a conserved Glu159 residue that is essential for CD39 activity inhibited ATPase and ADPase activity of Lpg1905. In addition, enzyme activity was inhibited in the presence of the specific ecto‐NTPDase inhibitor, ARL67156. The entry and replication defect of the lpg1905 mutant was reversed upon transcomplementation with lpg1905 but not lpg1905E159A encoding an enzymatically inactive form of the protein. Although several protozoan parasites exhibit ecto‐NTPDase activity, including Toxoplasma gondii , Trichomonas vaginalis and Trypanosoma cruzi , this is the first time a bacterial ecto‐NTPDase has been implicated in virulence.