Phospholipase PlaB is a new virulence factor of Legionella pneumophila.
We previously identified Legionella pneumophila PlaB as the major cell-associated phospholipase A/lysophospholipase A with contact-dependent hemolytic activity. In this study, we further characterized this protein and found it to be involved in the virulence of L. pneumophila. PlaB was mainly expressed and active during exponential growth. Active PlaB was outer membrane-associated and at least in parts surface-exposed. Transport to the outer membrane was not dependent on the type I (T1SS), II (T2SS), IVB (T4BSS) or Tat secretion pathways. Furthermore, PlaB activity was not dependent on the presence of the macrophage infectivity potentiator (Mip) or the major secreted zinc metalloproteinase A (MspA). Despite the fact that PlaB is not essential for replication in protozoa or macrophage cell lines, we found that plaB mutants were impaired for replication in the lungs and dissemination to the spleen in the guinea pig infection model. Histological sections monitored less inflammation and destruction of the lung tissue after infection with the plaB mutants compared to L. pneumophila wild type. Taken together, PlaB is the first phospholipase A/lysophospholipase A with a confirmed role in the establishment of Legionnaires' disease.
Robert Koch-Institut, Research Group P26, Nosocomial Infections of the Elderly, Nordufer 20, 13353 Berlin, Germany.
Eva
E
Schunder
Patrick
P
Adam
Futoshi
F
Higa
Katharina A
KA
Remer
Udo
U
Lorenz
Jennifer
J
Bender
Tino
T
Schulz
Antje
A
Flieger
Michael
M
Steinert
Klaus
K
Heuner
D000818:Animals; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics / Q000502:physiology*; D004195:Disease Models, Animal; D020869:Gene Expression Profiling; D055786:Gene Knockout Techniques; D006168:Guinea Pigs; D006651:Histocytochemistry; D016952:Legionella pneumophila / Q000201:enzymology* / Q000254:growth & development / Q000472:pathogenicity*; D007877:Legionnaires' Disease / Q000382:microbiology; D008168:Lung / Q000382:microbiology / Q000473:pathology; D008297:Male; D010740:Phospholipases / Q000235:genetics / Q000502:physiology*; D013154:Spleen / Q000382:microbiology; D014774:Virulence; D037521:Virulence Factors / Q000502:physiology*
D001425:Bacterial Outer Membrane Proteins; D037521:Virulence Factors; D010740:Phospholipases