engleski

Differential accumulation of plastid preprotein translocon components during spruce (Picea abies L. Karst.) needle development

We demonstrate that basic components of plastid protein import apparatus originally found in pea, Toc34, Toc159, and Tic110, are also conserved in evolutionary younger gymnosperms. We show that multiple isoforms of preprotein receptor Toc34 differentially accumulate in various stages of needle development, while the amounts of Toc159 drastically decrease during chloroplast morphogenesis. Spruce Toc34 and Toc159 receptors are able to recognize and interact with angiosperm precursor of Rubisco small subunit. Young proplastids found in closed buds contain a highly elevated number of protein translocation machineries equipped with only two types of outer envelope receptors Toc159 and a 30 kDa Toc34-related protein. The photosystem II (PSII) can be assembled in a fully functional complex already at this very early stage of needle development, suggesting that no additional receptor isoforms are needed for translocation of all necessary PSII components. We conclude that the accumulation of evolutionary conserved plastid preprotein translocation components is differentially regulated during spruce needle development.

plastid biogenesis; proplastids; protein translocation; Tic; Toc

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