The sortase SrtA of Listeria monocytogenes is involved in processing of internalin and in virulence.
Listeria monocytogenes is an intracellular gram-positive human pathogen that invades eucaryotic cells. Among the surface-exposed proteins playing a role in this invasive process, internalin belongs to the family of LPXTG proteins, which are known to be covalently linked to the bacterial cell wall in gram-positive bacteria. Recently, it has been shown in Staphylococcus aureus that the covalent anchoring of protein A, a typical LPXTG protein, is due to a cysteine protease, named sortase, required for bacterial virulence. Here, we identified in silico from the genome of L. monocytogenes a gene, designated srtA, encoding a sortase homologue. The role of this previously unknown sortase was studied by constructing a sortase knockout mutant. Internalin was used as a reporter protein to study the effects of the srtA mutation on cell wall anchoring of this LPXTG protein in L. monocytogenes. We show that the srtA mutant (i) is affected in the display of internalin at the bacterial surface, (ii) is significantly less invasive in vitro, and (iii) is attenuated in its virulence in the mouse. These results demonstrate that srtA of L. monocytogenes acts as a sortase and plays a role in the pathogenicity.
Garandeau
Caroline
C
INSERM U-411, CHU Necker-Enfants Malades, 75730 Paris Cedex 15, France.
Réglier-Poupet
Hélène
H
Dubail
Iharilalao
I
Beretti
Jean-Luc
JL
Berche
Patrick
P
Charbit
Alain
A
D000595:Amino Acid Sequence; D019881:Aminoacyltransferases / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism*; D003546:Cysteine Endopeptidases; D005260:Female; D005798:Genes, Bacterial; D016680:Genome, Bacterial; D008089:Listeria monocytogenes / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity*; D051379:Mice; D008969:Molecular Sequence Data; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D021381:Protein Transport; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D012995:Solubility
D001426:Bacterial Proteins; C069761:internalin protein, Bacteria; D019881:Aminoacyltransferases; C120542:sortase A; D003546:Cysteine Endopeptidases