The Legionella pneumophila LidA protein: a translocated substrate of the Dot/Icm system associated with maintenance of bacterial integrity.
Legionella pneumophila establishes a replication vacuole within phagocytes that requires the bacterial Dot/Icm apparatus for its formation. This apparatus is predicted to translocate effectors into host cells. We hypothesized that some translocated proteins also function to maintain the integrity of the Dot/Icm translocator. Mutations that destroy this function are predicted to result in a Dot/Icm complex that poisons the bacterium, resulting in reduced viability. To identify such mutants, strains were isolated (called lid-) that showed reduced viability on bacteriological medium in the presence of an intact Dot/Icm apparatus, but which had high viability in the absence of the translocator. Several such mutants were analysed in detail to identify candidate strains that may have lost the ability to synthesize a translocated substrate of Dot/Icm. Two such strains had mutations in the lidA gene. The LidA protein exhibits properties expected for a translocated substrate of Dot/Icm that is important for maintenance of bacterial cell integrity: it associates with the phagosomal surface, promotes replication vacuole formation, and is important for both efficient intracellular growth and high viability on bacteriological media after introduction of a plasmid that allows high level expression of the dotA gene.
Conover
Gloria M
GM
Department of Molecular Biology and Microbiology, Tufts University School of Medicine,136 Harrison Ave M and V 409, Boston, MA, 02111, USA.
Derré
Isabelle
I
Vogel
Joseph P
JP
Isberg
Ralph R
RR
D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001854:Bone Marrow Cells / Q000166:cytology / Q000378:metabolism / Q000382:microbiology; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D005260:Female; D006801:Humans; D016952:Legionella pneumophila / Q000235:genetics / Q000378:metabolism*; D051907:Lysosomal Membrane Proteins; D008264:Macrophages / Q000166:cytology / Q000378:metabolism / Q000382:microbiology; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D026901:Membrane Transport Proteins / Q000378:metabolism*; D051379:Mice; D009154:Mutation; D010588:Phagosomes / Q000378:metabolism
D015703:Antigens, CD; D001426:Bacterial Proteins; D002352:Carrier Proteins; C440002:DotA protein, Legionella pneumophila; D051907:Lysosomal Membrane Proteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins