Phytolongins, a non-SNARE longins proteins family conserved in land plants. A bioinformatics study and a characterization of Arabidopsis thaliana (L.) mutants.

Subcellular trafficking in Eukaryotes is finely regulated, with the SNARE proteins regulating membrane fusion. Among vesicular SNAREs, longins are characterized by an N-terminal longin domain (LD) preceding the R-SNARE motif. Land plants genomes encode a conserved family of LD proteins, Phytolongins, with similarities to other longins and peculiar characteristics. These proteins share the N-terminal LD with all longins and the C-terminus with VAMP7-like ones. Nevertheless, in Phytolongins, the R-SNARE motif is replaced by a central, unknown-function PhyL region. As part of this project, we aim to obtain bioinformatic suggestions on possible function and evolution of the PhyL region. The Arabidopsis thaliana genome is endowed with four Phytolongins genes (Phyl1.1, Phyl1.2, Phyl2.1, Phyl2.2) and corresponding proteins are distributed along the secretory pathway. Based on conservation and amplification, Phytolongins genes are likely very important for land plants; however, their roles in development and physiology are still unknown. To shed light on Phytolongins’ roles in model plant species Arabidopsis thaliana, two knock-out mutants for Phyl1.1 and Phyl2.1 were purchased. These mutants have been characterized by phenotypization to assess any evident feature. Then, to follow up the Phytolongins genes expression in Arabidopsis’ wild type plants, quantitative real-time PCR (qRT-PCR) was performed.