Kutuzov M A, Andreeva A V
Research School of Biological and Molecular Sciences, Oxford Brookes University, Oxford, Headington, OX3 0BP, United Kingdom.
Biochem Biophys Res Commun. 2001 Apr 27;283(1):93-6. doi: 10.1006/bbrc.2001.4751.
Changes in the cytoplasmic inorganic phosphate (P(i)) concentrations are an important cue for the plant cells to regulate their metabolism and phosphate homeostasis. However, phosphate sensors/receptors involved in this regulation are largely unknown. P(i) is a common nonspecific competitive inhibitor of phosphatases, usually in millimolar range. Here we report a procedure to refold recombinant Arabidopsis thaliana protein Ser/Thr phosphatase PP7 and demonstrate that PP7 is inhibited by submillimolar P(i) concentrations (IC(50) = 0.66 +/- 0.14 mM) via a mainly noncompetitive mechanism. The results indicate that PP7 may possess a specific P(i)-binding site responsible for its allosteric regulation, and suggest a possible phosphate sensor function for this protein phosphatase.
细胞质中无机磷酸盐（P(i)）浓度的变化是植物细胞调节其新陈代谢和磷酸盐稳态的重要线索。然而，参与这种调节的磷酸盐传感器/受体在很大程度上尚不清楚。P(i) 是磷酸酶常见的非特异性竞争性抑制剂，通常处于毫摩尔范围内。在这里，我们报告了一种重折叠重组拟南芥蛋白丝氨酸/苏氨酸磷酸酶PP7的方法，并证明PP7受到亚毫摩尔浓度P(i)（IC(50) = 0.66 +/- 0.14 mM）的抑制，其机制主要是非竞争性的。结果表明，PP7可能具有一个负责其变构调节的特定P(i)结合位点，并提示这种蛋白磷酸酶可能具有磷酸盐传感器功能。
