Functional characterization of plant EXO70 exocyst subunit isoforms and their membrane targeting mechanisms

Vesicle tethering complex exocyst is one of the key regulators of the cell polarity and morphogenesis in eukaryotes. The complex interacts with the secretory vesicle, as well as plasma membrane, and facilitates formation of cis SNARE complex leading into fusion of the vesicle with target destination. Two of the eight exocyst subunits, the SEC3 and EXO70 are known to bind plasma membrane via protein and lipid interactors in Opisthokont model organisms. Genomes of angiosperm plants encode a surprisingly wide repertoire of EXO70 isoforms with over 20 present in both Arabidopsis and diploid tobacco genome. It has been proposed that different EXO70 isoforms would form parts of functionally distinct subtypes of the plant exocyst complex driving membrane trafficking to various membrane domains. Specific interactions of peripheral membrane proteins with particular membrane phospholipids largely contribute to targeting of cellular components to subcellular compartments and membrane domains. This thesis focuses on role of protein-lipid interactions in regulation of plant cell polarity and contributes to functional analysis of the plant EXO70 family diversity. We introduce the topic with the theoretical reviews summarizing role of protein-lipid interactions in establishing plant cell membrane domains at..