A plastid enzyme arrested in the step of precursor translocation in vivo.
A plastid enzyme arrested in the step of precursor translocation in vivo.
复制标题
在体内前体易位步骤中被阻滞的质体酶。
DOI：
10.1073/pnas.93.21.12026
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发表时间：
1996
影响因子：
11.1
通讯作者：
Klaus Apel
中科院分区：
文献类型：
--
作者：
S. Reinbothe;C. Reinbothe;Dieter Neumann;Klaus Apel
高等植物中叶绿素生物合成的关键酶NADPH：原叶绿素（Pchlide）氧化还原酶（POR，EC 1.3.1.33）以其前体形式（pPORA）积累在大麦中。pPORA与叶绿体结合，并能够在质体包膜的胞质侧和基质侧与酶的底物Pchlide相互作用。与含ATP的叶绿体中在喂饲-氨基酮戊酸后形成的质内Pchlide的相互作用驱动pPORA穿过质体被膜的载体移位。相比之下，外源性应用Pchlide导致释放的酶结合的前体蛋白质的胞质溶胶。如果同时应用质内和质外Pchlide，这两个过程相互竞争。然而，存在于小麦胚芽和大麦叶蛋白提取物中的Mr 70，000的胞质热休克同源蛋白似乎阻止pPORA在体内释放到胞质溶胶中。
The key enzyme of chlorophyll biosynthesis in higher plants, NADPH:protochlorophyllide (Pchlide) oxidoreductase (POR, EC 1.3.1.33), accumulates in its precursor form (pPORA) in barley. pPORA is bound to the chloroplasts and is able to interact with the enzyme's substrate, Pchlide, at both the cytosolic as well as the stromal side of the plastid envelope. The interaction with intraplastidic Pchlide, formed in ATP-containing chloroplasts upon feeding with -aminolevulinic acid, drives vectorial translocation of pPORA across the plastid envelope membranes. In contrast, exogenously applied Pchlide causes the release of the envelope-bound precursor protein to the cytosol. Both processes compete with each other if intra- and extraplastidic Pchlide are applied simultaneously. A cytosolic heat shock cognate protein of Mr 70,000 present in wheat germ and barley leaf protein extracts appears to prevent the release of the pPORA to the cytosol in vivo, however.