Ixodes ricinus Tick Lipocalins: Identification,Cloning, Phylogenetic Analysis and Biochemical Characterization |
| |
| Authors: | Jér?me Beaufays Beno?t Adam Yves Decrem Pierre-Paul Prév?t Sébastien Santini Robert Brasseur Michel Brossard Laurence Lins Luc Vanhamme Edmond Godfroid |
| |
| Affiliation: | 1. Laboratory for Molecular Biology of Ectoparasites, IBMM, Université Libre de Bruxelles, Gosselies, Belgium.; 2. Centre de Biophysique Moléculaire Numérique, Gembloux Agricultural University, Gembloux, Belgium.; 3. Institute of Zoology, University of Neuchâtel, Neuchâtel, Switzerland.; 4. Laboratory of Molecular Parasitology, IBMM, Université Libre de Bruxelles, Gosselies, Belgium.;Centre de Recherche Public-Santé, Luxembourg |
| |
| Abstract: | BackgroundDuring their blood meal, ticks secrete a wide variety of proteins that interfere with their host''s defense mechanisms. Among these proteins, lipocalins play a major role in the modulation of the inflammatory response.Methodology/Principal FindingsScreening a cDNA library in association with RT-PCR and RACE methodologies allowed us to identify 14 new lipocalin genes in the salivary glands of the Ixodes ricinus hard tick. A computational in-depth structural analysis confirmed that LIRs belong to the lipocalin family. These proteins were called LIR for “Lipocalin from I. ricinus” and numbered from 1 to 14 (LIR1 to LIR14). According to their percentage identity/similarity, LIR proteins may be assigned to 6 distinct phylogenetic groups. The mature proteins have calculated pM and pI varying from 21.8 kDa to 37.2 kDa and from 4.45 to 9.57 respectively. In a western blot analysis, all recombinant LIRs appeared as a series of thin bands at 50–70 kDa, suggesting extensive glycosylation, which was experimentally confirmed by treatment with N-glycosidase F. In addition, the in vivo expression analysis of LIRs in I. ricinus, examined by RT-PCR, showed homogeneous expression profiles for certain phylogenetic groups and relatively heterogeneous profiles for other groups. Finally, we demonstrated that LIR6 codes for a protein that specifically binds leukotriene B4.Conclusions/SignificanceThis work confirms that, regarding their biochemical properties, expression profile, and sequence signature, lipocalins in Ixodes hard tick genus, and more specifically in the Ixodes ricinus species, are segregated into distinct phylogenetic groups suggesting potential distinct function. This was particularly demonstrated by the ability of LIR6 to scavenge leukotriene B4. The other LIRs did not bind any of the ligands tested, such as 5-hydroxytryptamine, ADP, norepinephrine, platelet activating factor, prostaglandins D2 and E2, and finally leukotrienes B4 and C4. |
| |
| Keywords: | |
|
|
