Looking for unconventional secretion patterns in leaderless proteins of sunflower extracellular vesicles

REGENTE M; DE LA CANAL L; PINEDO M

Mar del Plata

Congreso; 9º Congreso Argentino de Bioinformática y Biología Computacional; 2018

9º Congreso Argentino de Bioinformática y Biología Computacional

Unconventional Protein Secretion has been recently accepted to operate in plants. The underlying mechanisms that drive these proteins tothe apoplast remain unknown, however, vesicular traffic emerge as a possibility. Recent proteomic analysis of extracellular vesicles (EV)showed that they contribute to defense and cell wall remodeling at the time that provides a dataset to look for evidence of the secretoryroute. Here, we investigate, the occurrence of patterns and common linear motifs within a set of sunflower unconventionally secretedproteins (SUSP). The SUSP were selected from EV proteomic data according to the following features: they have not subcellular locationidentified by TargetP 1.1 nor signal peptide detected by Signal P 4.1, and they are predicted to be apoplastic by both LocTree2 andApoplastP. The filtered proteins belonged to glycosyl hydrolases, jacalin lectins, PAN/Apple domains, Serin carboxypeptidase S10 and GDSLand PMR5 estearses families. Their Fasta sequences were locally aligned using Cobalt and a conserved region of 120 aa was identified inspite of the diversity of families contributing to SUSP. The frequency of aminoacids in the multiple alignment of the region was graphicallyrepresented using WebLogo3. This region was enriched in glycine and hydrophobic residues mainly Leucine and Phenyalanine. An artificialsequence was obtained with the residues of the highest frequency in each position along the logo that was predicted to be secreted byboth, LocTree2 and ApoplastP. The result suggests that the in silico procedure was able to capture a potential requirement for a protein tofollow unconventional secretion mediated by EV. In parallel, linear motifs were assessed with ELM software. Among the motifs identified inthe aligned region appeared the tyrosine-based sorting signal and the Canonical LC3-interacting region (LIR) that binds to the AdaptorProtein and Atg8 protein respectively pointing out to endocytic and/or autophagic related routes. Interestingly, the crosstalk of these routeshas been recently proposed