The PPIase active site of Legionella pneumophila Mip protein is involved in the infection of eukaryotic host cells.
We analysed eight monoclonal antibodies (mAbs) directed against the Mip (macrophage infectivity potentiator) protein, a virulence factor of the intracellular pathogen Legionella pneumophila. Mip belongs to the FK506-binding proteins (FKBPs) and exhibits peptidyl prolyl cis/trans isomerase (PPIase) activity. Five of the mAbs recognised epitopes in the C-terminal, FKBP-homologous domain of Mip, which is highly conserved among all Legionella species. Upon immunological binding to Mip, all but one of these mAbs caused inhibition of the PPIase activity in vitro. mAb binding to the N-terminal domain of Mip did not influence its enzymatic activity. All but one of the PPIase inhibiting mAbs were able to significantly inhibit the early establishment and initiation of an intracellular infection of the bacteria in Acanthamoeba castellanii, the natural host, and in the human phagocytic cell line U937. These data demonstrate for the first time that for the virulence-enhancing property of the L. pneumophila Mip protein, an intact active site of the enzyme is an essential requirement.
Helbig
Jürgen H
JH
Medizinische Fakultät der TU Dresden, Institut für Medizinische Mikrobiologie und Hygiene, Fetscherstr. 74, D-01307 Dresden, Germany.
König
Bettina
B
Knospe
Henry
H
Bubert
Birgit
B
Yu
Chao
C
Lück
Christian P
CP
Riboldi-Tunnicliffe
Alan
A
Hilgenfeld
Rolf
R
Jacobs
Enno
E
Hacker
Jörg
J
Fischer
Gunter
G
D000048:Acanthamoeba / Q000382:microbiology; D019943:Amino Acid Substitution / Q000235:genetics; D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry; D000954:Antigens, Surface / Q000235:genetics; D001426:Bacterial Proteins; D001665:Binding Sites; D001666:Binding Sites, Antibody / Q000235:genetics; D002460:Cell Line; D003470:Culture Media; D004591:Electrophoresis, Polyacrylamide Gel; D004797:Enzyme-Linked Immunosorbent Assay; D018604:Epitope Mapping; D004926:Escherichia coli / Q000378:metabolism; D029968:Escherichia coli Proteins; D005057:Eukaryotic Cells / Q000382:microbiology; D006801:Humans; D015151:Immunoblotting; D007074:Immunoglobulin G / Q000235:genetics; D020104:Immunophilins / Q000737:chemistry*; D007700:Kinetics; D016952:Legionella pneumophila / Q000201:enzymology* / Q000472:pathogenicity; D007877:Legionnaires' Disease / Q000201:enzymology / Q000382:microbiology*; D008264:Macrophages / Q000382:microbiology; D008565:Membrane Proteins / Q000737:chemistry*; D019696:Peptidylprolyl Isomerase / Q000737:chemistry*; D010957:Plasmids / Q000235:genetics; D020349:Surface Plasmon Resonance
D000911:Antibodies, Monoclonal; D000954:Antigens, Surface; D001426:Bacterial Proteins; D003470:Culture Media; D029968:Escherichia coli Proteins; D007074:Immunoglobulin G; D008565:Membrane Proteins; D020104:Immunophilins; C512922:Mip protein, Legionella pneumophila; D019696:Peptidylprolyl Isomerase; C068254:FkpA protein, E coli