Analysis of tail-anchored protein translocation pathway in plants

Abstract

Tail-anchored (TA) proteins are a special class of membrane proteins that carry out vital functions in all living cells. Targeting mechanisms of TA proteins are investigated as the best example for post-translational protein targeting in yeast. Of the several mechanisms, Guided Entry of Tail-anchored protein (GET) pathway plays a major role in TA protein targeting. Many in silico and in vivo analyses are geared to identify TA proteins and their targeting mechanisms in different systems including Arabidopsis thaliana. Yet, crop plants that grow in specific and/or different conditions are not investigated for the presence of TA proteins and GET pathway. This study majorly investigates GET pathway in two crop plants, Oryza sativa subsp. Indica and Solanum tuberosum, through detailed in silico analysis. 508 and 912 TA proteins are identified in Oryza sativa subsp. Indica and Solanum tuberosum respectively and their localization with respect to endoplasmic reticulum (ER), mitochondria, and chloroplast has been delineated. Similarly, the associated GET proteins are identified (Get1, Get3 and Get4) and their structural inferences are elucidated using homology modelling. Get3 models are based on yeast Get3. The cytoplasmic Get3 from O. sativa is identified to be very similar to yeast Get3 with conserved P-loop and TA binding groove. Three cytoplasmic Get3s are identified for S. tuberosum. Taken together, this is the first study to identify TA proteins and GET components in Oryza sativa subsp. Indica and Solanum tuberosum, forming the basis for any further experimental characterization of TA targeting and GET pathway mechanisms in crop plants.

Structures of Get3d reveal a distinct architecture associated with the emergence of photosynthesis

“…Recent work explores the GET pathway in plants, with all components of the GET pathway excluding Get5 and Sgt2 having been identified ( 18 , 19 , 20 , 23 , 57 ). However, a striking difference in plants compared with other eukaryotes is the presence of multiple paralogs of Get3 ( 8 , 17 , 19 ). In A. thaliana , four paralogs of Get3 exist, termed Get3a–d.…”

“…Get3 has been shown to have a conserved mechanism across eukaryotes ( 5 , 6 ). Many TA proteins play essential roles, for example, vesicle trafficking, protein localization, and regulation of apoptosis, and are targeted to various membranes ( 7 , 8 ).…”

“…in 2012 ( 17 ) with a distinct architecture characterized by an α-crystallin domain (αCD) at its C terminus. Unlike fungi and metazoa, which contain a single Get3 in each genome, plants and cyanobacteria have multiple Get3 genes ( 8 , 17 , 18 , 19 , 20 ). The model plant Arabidopsis thaliana ( A. thaliana ) contains four such genes (noted Get3a, b, c, and d).…”