Spano A J, He Z, Michel H, Hunt D F, Timko M P
Department of Biology, University of Virginia, Charlottesville 22901.
Plant Mol Biol. 1992 Mar;18(5):967-72. doi: 10.1007/BF00019210.
Complementary DNA clones and a corresponding nuclear gene (lpcr) encoding the NADPH-dependent protochlorophyllide oxidoreductase (pchlide reductase, EC 1.6.99.1) have been characterized from pea (Pisum sativum L.). The pea lpcr gene encodes a 43,118 Da precursor polypeptide comprised of a transit peptide of 64 amino acids and a mature protein of 336 amino acids. The coding portion of the gene is interrupted by four introns, two of which are located within the transit peptide coding portion of the gene. The deduced primary structure for the pea protein is similar to those reported for Arabidopsis and two monocot species. Northern blot analysis revealed little to no decrease in steady-state levels of mRNA encoding the enzyme in etiolated leaves illuminated with continuous white light for up to 48 h. In contrast, western blot analysis showed that the major immunoreactive species present in whole leaf extracts decreased to nearly undetectable levels during this same 48 h period. These results suggest that pchlide reductase activity in pea is primarily regulated post-transcriptionally, most likely at the level of translation initiation/elongation or protein turnover.
已从豌豆（Pisum sativum L.）中鉴定出互补DNA克隆以及编码依赖NADPH的原叶绿素酸氧化还原酶（原叶绿素酸还原酶，EC 1.6.99.1）的相应核基因（lpcr）。豌豆lpcr基因编码一种43,118 Da的前体多肽，由64个氨基酸的转运肽和336个氨基酸的成熟蛋白组成。该基因的编码部分被四个内含子打断，其中两个位于基因的转运肽编码部分内。推导的豌豆蛋白一级结构与拟南芥和两个单子叶植物物种报道的结构相似。Northern印迹分析表明，在用连续白光照射长达48小时的黄化叶片中，编码该酶的mRNA稳态水平几乎没有下降。相反，蛋白质印迹分析表明，在相同的48小时期间，全叶提取物中存在的主要免疫反应性物种下降到几乎无法检测的水平。这些结果表明，豌豆中原叶绿素酸还原酶的活性主要在转录后受到调节，最有可能在翻译起始/延伸或蛋白质周转水平上。
