A Plant-Specific N-terminal Extension Reveals Evolutionary Functional Divergence within Translocator Proteins.
(2020) iScience — Vol. 23, n° 3, p. 100889 (2020)
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- Conserved translocator proteins (TSPOs) mediate cell stress responses possibly in a cell-type-specific manner. This work reports on the molecular function of plant TSPO and their possible evolutionary divergence. Arabidopsis thaliana TSPO (AtTSPO) is stress induced and has a conserved polybasic, plant-specific N-terminal extension. AtTSPO reduces water loss by depleting aquaporin PIP2;7 in the plasma membrane. Herein, AtTSPO was found to bind phosphoinositides in vitro, but only full-length AtTSPO or chimeric mouse TSPO with an AtTSPO N-terminus bound PI(4,5)Pin vitro and modified PIP2;7 levels in vivo. Expression of AtTSPO but not its N-terminally truncated variant enhanced phospholipase C activity and depleted PI(4,5)P from the plasma membrane and its enrichment in Golgi membranes. Deletion or point mutations within the AtTSPO N-terminus affected PI(4,5)P binding and almost prevented AtTSPO-PIP2;7 interaction in vivo. The findings imply functional divergence of plant TSPOs from bacterial and animal counterparts via evolutionary acquisition of the phospholipid-interacting N-terminus.
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Jurkiewicz, P., Senicourt, L., Ayeb, H., Lequin, O., Lacapere, J.-J., & Batoko, H. (2020). A Plant-Specific N-terminal Extension Reveals Evolutionary Functional Divergence within Translocator Proteins. iScience, 23(3), 100889. https://doi.org/10.1016/j.isci.2020.100889 (Original work published 2020)