LPXTG protein InlJ, a newly identified internalin involved in Listeria monocytogenes virulence.
Listeria monocytogenes expresses surface proteins covalently anchored to the peptidoglycan by sortase enzymes. Inactivation of srtA attenuates Listeria virulence in mice (H. Bierne, S. K. Mazmanian, M. Trost, M. G. Pucciarelli, G. Liu, P. Dehoux, L. Jansch, F. Garcia-del Portillo, O. Schneewind, and P. Cossart, Mol. Microbiol. 43:869-881, 2002). We show here that an srtA mutant is more attenuated than an internalin mutant in orally infected guinea pigs and transgenic mice expressing human E-cadherin (hEcad mice), indicating the involvement of other SrtA substrates, LPXTG proteins, in food-borne listeriosis. Data recently generated with a listerial DNA macroarray identified two LPXTG protein-encoding genes present in the genomes of L. monocytogenes strains and absent from all other Listeria species, inlI (lmo0333) and inlJ (lmo2821). They also revealed two other LPXTG protein-encoding genes, ORF29 and ORF2568, present only in a subclass of L. monocytogenes serovars, including the epidemic serovar 4b. We report here that an inlJ deletion mutant, in contrast to inlI and ORF29 mutants, is significantly attenuated in virulence after intravenous infection of mice or oral inoculation of hEcad mice. Interestingly, a DeltaORF2568 strain showed a slight increase in virulence. inlJ encodes a leucine-rich repeat (LRR) protein that is structurally related to the listerial invasion factor internalin. However, the consensus sequence of the InlJ LRR defines a novel subfamily of cysteine-containing LRRs in bacteria. In conclusion, this postgenomic approach identified InlJ as a new virulence factor among the proteins belonging to the internalin family in L. monocytogenes.
Sabet
Christophe
C
Unité des Interactions Bactéries-Cellules, Institut Pasteur, INSERM U604, INRA USC2020, Paris, France.
Lecuit
Marc
M
Cabanes
Didier
D
Cossart
Pascale
P
Bierne
Hélène
H
D000595:Amino Acid Sequence; D019881:Aminoacyltransferases / Q000235:genetics / Q000502:physiology; D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D003546:Cysteine Endopeptidases; D020868:Gene Silencing; D006168:Guinea Pigs; D008089:Listeria monocytogenes / Q000235:genetics* / Q000472:pathogenicity*; D008088:Listeriosis / Q000382:microbiology*; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D051379:Mice; D008969:Molecular Sequence Data; D011487:Protein Conformation; D014774:Virulence / Q000235:genetics
D001426:Bacterial Proteins; D008565:Membrane Proteins; C069761:internalin protein, Bacteria; D019881:Aminoacyltransferases; C120542:sortase A; D003546:Cysteine Endopeptidases