Departamento de Biología Vegetal, Facultad de Biología, Universidad de Sevilla, Avenida Reina Mercedes nº 6, 41012, Seville, Spain.
Centro de Biotecnología y Genómica de Plantas, Universidad Politécnica de Madrid, Campus de Montegancedo, Autovía M40 (km 38), Pozuelo de Alarcón, 28034, Madrid, Spain.
Planta. 2021 Aug 5;254(3):43. doi: 10.1007/s00425-021-03692-3.
A synthetic peptide from the C-terminal end of C-phosphoenolpyruvate carboxylase is implicated in the proteolysis of the enzyme, and Glc-6P or phosphorylation of the enzyme modulate this effect. Phosphoenolpyruvate carboxylase (PEPC) is a cytosolic, homotetrameric enzyme that performs a variety of functions in plants. Among them, it is primarily responsible for CO fixation in the C photosynthesis pathway (C-PEPC). Here we show that proteolysis of C-PEPC by cathepsin proteases present in a semi-purified PEPC fraction was enhanced by the presence of a synthetic peptide containing the last 19 amino acids from the C-terminal end of the PEPC subunit (pC19). Threonine (Thr)944 and Thr948 in the peptide are important requirements for the pC19 effect. C-PEPC proteolysis in the presence of pC19 was prevented by the PEPC allosteric effector glucose 6-phosphate (Glc-6P) and by phosphorylation of the enzyme. The role of these elements in the regulation of PEPC proteolysis is discussed in relation to the physiological context.
一种来自 C-磷酸烯醇丙酮酸羧激酶 C 末端的合成肽与该酶的蛋白水解有关，并且 Glc-6P 或该酶的磷酸化调节这种效应。磷酸烯醇丙酮酸羧激酶（PEPC）是一种胞质同型四聚体酶，在植物中具有多种功能。其中，它主要负责 C 光合作用途径（C-PEPC）中的 CO 固定。在这里，我们表明，半纯化的 PEPC 级分中存在的组织蛋白酶蛋白酶对 C-PEPC 的蛋白水解作用通过存在包含 PEPC 亚基 C 末端最后 19 个氨基酸的合成肽（pC19）而增强。肽中的苏氨酸（Thr）944 和 Thr948 是 pC19 效应的重要要求。在 pC19 存在下，C-PEPC 的蛋白水解作用被 PEPC 变构效应物葡萄糖 6-磷酸（Glc-6P）和该酶的磷酸化所阻止。讨论了这些元素在调节 PEPC 蛋白水解中的作用与生理背景的关系。
