多聚磷酸盐聚合酶VTC复合体的结构和功能

磷酸盐(P_i)稳态在所有生物体中都是一个受严格调控的过程，其功能障碍会导致人类肾范科尼综合征(Fanconi syndrome)、植物生长迟缓和微生物致死等多种功能紊乱。为了在P_i的生物合成需求和胞质P_i浓度过高的风险之间实现平衡，细胞以无机多聚磷酸盐(polyP)的形式将P_i储存在膜结合的酸钙小体样细胞器中。酿酒酵母液泡转运蛋白伴侣(vacuolar transporter chaperone,VTC)复合体作为已知的真核生物多聚磷酸盐聚合酶，利用ATP在胞质中合成polyP，并将其转运到液泡中储存起来以维持细胞内P_i稳态。本文从结构特征、polyP合成及polyP转运机制等方面介绍了VTC复合体结构和功能的最新研究进展，着重介绍了最近发表的完整VTC复合体的结构信息，并探讨了VTC的激活机制。

Structure and Function of Polyphosphate Polymerase VTC Complex

Phosphate (P_i) homeostasis is a tightly regulated process in all organisms. Dysfunction of P_i homeostasis leads to renal Fanconi syndrome in humans, severe growth retardation in plants, and lethality in microorganisms. To achieve a delicate balance between the biosynthetic requirements for P_i and the risks of excessive cytoplasmic P_i, unicellular organisms maintain important P_i stores in membrane-bound, acidocalcisome-like organelles in the form of inorganic polyphosphates (polyP). As the only known eukaryotic polyP synthetase, Saccharomyces cerevisiae vacuolar transporter chaperone (VTC) complex synthesizes polyP from adenosine triphosphate (ATP) and translocates polyP across the vacuolar membrane to maintain an intracellular P_i homeostasis. In this article, the latest progress on the structure and function of VTC complexes were reriewed from the aspects of structural characteristics, polyP synthesis, and polyP transport mechanism. The focus is on the recently published intact structural of VTC complexes and exploring the activation mechanism of VTC.