A bacterial ecto-triphosphate diphosphohydrolase similar to human CD39 is essential for intracellular multiplication of Legionella pneumophila.
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.
Sansom
Fiona M
FM
Australian Bacterial Pathogenesis Program, Department of Microbiology, Monash University, Victoria 3800, Australia.
Newton
Hayley J
HJ
Crikis
Sandra
S
Cianciotto
Nicholas P
NP
Cowan
Peter J
PJ
d'Apice
Anthony J F
AJ
Hartland
Elizabeth L
EL
D000251:Adenosine Triphosphatases / Q000235:genetics / Q000502:physiology*; D000595:Amino Acid Sequence; D000818:Animals; D015703:Antigens, CD / Q000235:genetics*; D001081:Apyrase / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics / Q000494:pharmacology / Q000502:physiology*; D001693:Biological Transport, Active; D002460:Cell Line; D019295:Computational Biology; D004847:Epithelial Cells / Q000378:metabolism / Q000382:microbiology; D006249:Hartmannella / Q000382:microbiology; D006801:Humans; D066298:In Vitro Techniques; D016952:Legionella pneumophila / Q000201:enzymology / Q000302:isolation & purification / Q000502:physiology*; D008969:Molecular Sequence Data; D009000:Monocytes / Q000378:metabolism / Q000382:microbiology; D009154:Mutation; D010974:Platelet Aggregation; D011755:Pyrophosphatases / Q000235:genetics / Q000494:pharmacology / Q000502:physiology*; D011994:Recombinant Proteins / Q000494:pharmacology; D037521:Virulence Factors / Q000235:genetics / Q000302:isolation & purification / Q000502:physiology
D015703:Antigens, CD; D001426:Bacterial Proteins; D011994:Recombinant Proteins; D037521:Virulence Factors; D000251:Adenosine Triphosphatases; D011755:Pyrophosphatases; D001081:Apyrase; C067869:CD39 antigen