Legionella pneumophila is a facultative intracellular parasite which is able to survive in various eukaryotic cells. We characterised a Tn5-mutant of the L. pneumophila Corby strain and were able to identify the insertion site of the transposon. It is localised within an open reading frame which shows high homology to the α-subunit of the oxaloacetate decarboxylase (OadA) of Klebsiella pneumoniae. The OadA homologous protein of L. pneumophila was detected in the wild-type strain by Western blotting. Since the intracellular multiplication of the oadA− mutant strain is reduced in guinea pig alveolar macrophages and human monocytes, it is concluded that the oadA gene product has an effect on the intracellular survival of L. pneumophil
