Affiliation:
1. Department of Pathology and Laboratory Medicine1 and
2. First Department of Internal Medicine, Faculty of Medicine, University of the Ryukyus, Okinawa 903-0215, Japan2
3. Department of Medicine,3 University of Pennsylvania Medical School, Philadelphia, PA 19104-4283, and
Abstract
ABSTRACT
We previously identified the
Legionella pneumophila ptsP
(phosphoenolpyruvate phosphotransferase) ortholog gene as a putative virulence factor in a study of signature-tagged mutagenesis using a guinea pig pneumonia model. In this study, we further defined the phenotypic properties of
L. pneumophila ptsP
and its complete sequence. The
L. pneumophila ptsP
was 2,295 bases in length. Its deduced amino acid sequence had high similarity with
ptsP
orthologs of
Pseudomonas aeruginosa, Azotobacter vinelandii
, and
Escherichia coli
, with nearly identical lengths. Here we show that while the mutant grew well in laboratory media, it was defective in both lung and spleen multiplication in guinea pigs. It grew slowly in guinea pig alveolar macrophages despite good uptake into the cells. Furthermore, there was minimal growth in a human alveolar epithelial cell line (A549). Transcomplementation of the
L. pneumophila ptsP
mutant almost completely rescued its growth in alveolar macrophages, in A549 cells, and in guinea pig lung and spleen. The
L. pneumophila ptsP
mutant was capable of evasion of phagosome-lysosome fusion and resided in ribosome-studded phagosomes. Pore formation activity of the mutant was normal. The
L. pneumophila ptsP
mutant expressed DotA and IcmX in apparently normal amounts, suggesting that the
ptsP
mutation did not affect
dotA
and
icmX
regulation. In addition, the mutant was resistant to serum and neutrophil killing. Taken together, these findings show that
L. pneumophila ptsP
is required for full in vivo virulence of
L. pneumophila
, most probably by affecting intracellular growth.
Publisher
American Society for Microbiology
Subject
Infectious Diseases,Immunology,Microbiology,Parasitology
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