Aronsson H, Sohrt K, Soll J
Department of Plant Physiology, Göteborg University, Sweden.
Biol Chem. 2000 Dec;381(12):1263-7. doi: 10.1515/BC.2000.155.
Chloroplast differentiation in angiosperm plants depends on the light-dependent conversion of protochlorophyllide to chlorophyllide by NADPH:protochlorophyllide oxidoreductase (PORA; EC 1.6.99.1), a nuclearly encoded protein. The protein import of the precursor form of PORA into plastids was shown previously to strictly depend on the presence of its substrate protochlorophyllide. PORA seemed to follow a novel, posttranslationally regulated import route. Here we demonstrate that the precursor of PORA from barley is imported into isolated barley plastids independently of protochlorophyllide. PORA as well as PORB import is competed for by the precursor of the small subunit of Rubisco. The data demonstrate that the PORA precursor uses the general import pathway into plastids. Furthermore, en route into chloroplasts the pea POR precursor can be cross-linked to the protein import channel in the outer envelope Toc75 from pea.
被子植物中的叶绿体分化依赖于由NADPH：原叶绿素酸氧化还原酶（PORA；EC 1.6.99.1，一种核编码蛋白）将原叶绿素酸光依赖性转化为叶绿素酸。先前已表明，PORA前体形式进入质体的蛋白质转运严格依赖于其底物原叶绿素酸的存在。PORA似乎遵循一种新的、翻译后调控的转运途径。在这里，我们证明大麦的PORA前体可独立于原叶绿素酸导入分离的大麦质体。PORA以及PORB的导入受到核酮糖-1,5-二磷酸羧化酶小亚基前体的竞争。数据表明，PORA前体利用进入质体的一般转运途径。此外，在进入叶绿体的途中，豌豆POR前体可与豌豆外膜Toc75中的蛋白质转运通道交联。
