Unravelling Different Biological Roles Of Plant Synaptotagmins
Endoplasmic Reticulum-Plasma Membrane contact sites (ER-PM CS) are evolutionarily conserved membrane domains found in all eukaryotes, where the endoplasmic reticulum (ER) closely interfaces with the plasma membrane (PM). This short distance, typically 10-30 nm, is achieved in Arabidopsis through the action of tether proteins such as Synaptotagmins (SYTs). Arabidopsis comprises five SYT members (SYT1-SYT5), but whether they possess overlapping or distinct biological functions remains elusive. SYT1 is the best-characterized gene member and plays an essential role in the resistance to abiotic stress. This study reveals that while the functionally redundant SYT1 and SYT3 genes are involved in salt and cold stress resistance, SYT5 is associated with Pseudomonas syringae resistance despite evidence of in vivo interaction between SYT1 and SYT5. Structural phylogenetic analysis indicates that SYT1 and SYT5 clades emerged early in the evolution of land plants. These protein clades exhibit different structural features, rationalizing their distinct biological roles.