Understanding the evolutionary structural variability and target specificity of tick salivary Kunitz peptides using next generation transcriptome data

0430607 - BC 2015 RIV GB eng J - Journal Article
Schwarz, Alexandra - Cabezas Cruz, Alejandro - Kopecký, Jan - Valdés, James J.
Understanding the evolutionary structural variability and target specificity of tick salivary Kunitz peptides using next generation transcriptome data.
BMC Evolutionary Biology. Roč. 14, JAN 2014 (2014), s. 4. ISSN 1471-2148. E-ISSN 1471-2148
R&D Projects: GA ČR GPP302/11/P798; GA MŠMT LH12002; GA ČR GAP302/12/2208; GA MŠMT(CZ) EE2.3.30.0032
Institutional support: RVO:60077344
Keywords : Red Queen hypothesis * tick saliva * Kunitz-domain proteins * cysteine motif * structural bioinformatics
Subject RIV: EC - Immunology
Impact factor: 3.368, year: 2014

Background: Ticks are blood-sucking arthropods and a primary function of tick salivary proteins is to counteract the host's immune response. Tick salivary Kunitz-domain proteins perform multiple functions within the feeding lesion and have been classified as venoms; thereby, constituting them as one of the important elements in the arms race with the host. The two main mechanisms advocated to explain the functional heterogeneity of tick salivary Kunitz-domain proteins are gene sharing and gene duplication. Both do not, however, elucidate the evolution of the Kunitz family in ticks from a structural dynamic point of view. The Red Queen hypothesis offers a fruitful theoretical framework to give a dynamic explanation for host-parasite interactions. Using the recent salivary gland Ixodes ricinus transcriptome we analyze, for the first time, single Kunitz-domain encoding transcripts by means of computational, structural bioinformatics and phylogenetic approaches to improve our understanding of the structural evolution of this important multigenic protein family. Results: Organizing the l. ricinus single Kunitz-domain peptides based on their cysteine motif allowed us to specify a putative target and to relate this target specificity to Illumina transcript reads during tick feeding. We observe that several of these Kunitz peptide groups vary in their translated amino acid sequence, secondary structure, antigenicity, and intrinsic disorder, and that the majority of these groups are subject to a purifying (negative) selection. We finalize by describing the evolution and emergence of these Kunitz peptides. The overall interpretation of our analyses discloses a rapidly emerging Kunitz group with a distinct disulfide bond pattern from the l. ricinus salivary gland transcriptome.
Permanent Link: http://hdl.handle.net/11104/0235516