The pyruvate, orthophosphate dikinase regulatory proteins of Arabidopsis possess a novel, unprecedented Ser/Thr protein kinase primary structure
The pyruvate, orthophosphate dikinase regulatory proteins of Arabidopsis possess a novel, unprecedented Ser/Thr protein kinase primary structure
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DOI：
10.1111/j.1365-313x.2007.03366.x
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发表时间：
2008-03-01
期刊：
影响因子：
7.2
通讯作者：
Chollet, Raymond
中科院分区：
文献类型：
--
作者：
Chastain, Chris J.;Xu, Wenxin;Chollet, Raymond
丙酮酸正磷酸二激酶（PPDK）是C3植物中普遍存在的一种低丰度的代谢酶，其功能尚未确定。其在C3叶绿体中的活性通过PPDK调节蛋白（RP）（一种最不寻常的双功能蛋白激酶（PK）/蛋白磷酸酶（PP））对活性位点Thr残基的可逆磷酸化进行光调节。在本文中，我们文件的分子克隆和功能分析的两个独特的C3 RPs的拟南芥。其中第一个，AtRP 1，编码一个典型的叶绿体靶向，双功能C4-样RP。第二个RP基因，AtRP 2，编码一种单功能多肽，具有体外RP样PK活性，但缺乏PP活性，并定位于胞质溶胶中。值得注意的是，这两个高度同源的多肽的推导的一级结构是缺乏任何典型的亚结构域结构，统一所有已知的真核和原核的丝氨酸/苏氨酸PKs到三个超家族之一，尽管直接证明AtRP 1是功能上的该组的成员。相反，这些C3 RP和相关的C4植物同源物编码一个保守的、位于中心的、大约260个残基的序列，目前被描述为“（d）在bar omain下，（u）在bar nknown下，（f）在bar 299下”（DUF 299）。我们建议，维管植物RP形成一个独特的蛋白激酶家族，现在指定为DUF 299基因家族。
Pyruvate, orthophosphate dikinase (PPDK) is a ubiquitous, low-abundance metabolic enzyme of undetermined function in C3 plants. Its activity in C3 chloroplasts is light-regulated via reversible phosphorylation of an active-site Thr residue by the PPDK regulatory protein (RP), a most unusual bifunctional protein kinase (PK)/protein phosphatase (PP). In this paper we document the molecular cloning and functional analysis of the two unique C3 RPs in Arabidopsis thaliana. The first of these, AtRP1, encodes a typical chloroplast-targeted, bifunctional C4-like RP. The second RP gene, AtRP2, encodes a monofunctional polypeptide that possesses in vitro RP-like PK activity but lacks PP activity, and is localized in the cytosol. Notably, the deduced primary structures of these two highly homologous polypeptides are devoid of any canonical subdomain structure that unifies all known eukaryotic and prokaryotic Ser/Thr PKs into one of three superfamilies, despite the direct demonstration that AtRP1 is functionally a member of this group. Instead, these C3 RPs and the related C4 plant homologues encode a conserved, centrally positioned, approximately 260-residue sequence currently described as the '(d) under bar omain of (u) under bar nknown (f) under bar unction 299' (DUF 299). We propose that vascular plant RPs form a unique protein kinase family now designated as the DUF 299 gene family.