Spano A J, He Z, Timko M P
Department of Biology, University of Virginia, Charlottesville 22901.
Mol Gen Genet. 1992 Dec;236(1):86-95.
protochlorophyllide oxidoreductase (pchlide reductase, EC 1.6.99.1) catalyzes the light-dependent reduction of protochlorophyllide in higher plants. Cloned cDNAs encoding two distinct pchlide reductases were isolated from a lambda gt11 library constructed from poly(A)+ RNA prepared from the cotyledons of dark-grown white pine (Pinus strobus) seedlings and a nuclear gene (lpcr) analogous to one of these cDNAs has been characterized from loblolly pine (P. taeda). The pine gene encodes an approximately 43 kDa precursor polypeptide consisting of a 334-amino acid mature protein and a 66-amino acid transit peptide. The deduced primary structures for the pine proteins are highly homologous to those reported from monocots and dicots. The coding portion of the pine lpcr gene is interrupted by four introns. The placement of these introns within the pine lpcr gene is identical to that observed in pea (Pisum sativum), suggesting conservation in gene organization between dicot and gymnosperm species. Western blot analysis using polyclonal antiserum against oat pchlide reductase detected in extracts of dark-grown pine cotyledons a single immunoreactive protein, which declined in abundance during a 48 h period of illumination with white light. Cotyledons of dark-grown seedlings were also found to accumulate high levels of pchlide reductase mRNA; however, little or no change in the steady-state levels of mRNA encoding pchlide reductase was observed in these tissues following illumination. Stem tissue of dark-grown seedlings did not contain significant levels of pchlide reductase mRNA, whereas stems of light-grown plants of the same age accumulated substantial amounts of the message. These results suggest that light and the developmental age of the tissue affect regulation of lpcr expression in pine.
烟酰胺腺嘌呤二核苷酸磷酸（NADPH）：原叶绿素酸酯氧化还原酶（原叶绿素酸酯还原酶，EC 1.6.99.1）催化高等植物中原叶绿素酸酯的光依赖性还原反应。从由黑暗生长的白松（北美乔松）幼苗子叶制备的聚腺苷酸加尾RNA构建的λgt11文库中分离出编码两种不同原叶绿素酸酯还原酶的克隆cDNA，并且已从火炬松中鉴定出与这些cDNA之一类似的核基因（lpcr）。松树基因编码一种约43 kDa的前体多肽，由一个334个氨基酸的成熟蛋白和一个66个氨基酸的转运肽组成。松树蛋白推导的一级结构与单子叶植物和双子叶植物报道的结构高度同源。松树lpcr基因的编码部分被四个内含子中断。这些内含子在松树lpcr基因中的位置与在豌豆中观察到的相同，表明双子叶植物和裸子植物物种之间基因组织具有保守性。使用针对燕麦原叶绿素酸酯还原酶的多克隆抗血清进行的蛋白质印迹分析在黑暗生长的松树子叶提取物中检测到一种单一的免疫反应性蛋白，该蛋白在白光照射48小时期间丰度下降。还发现黑暗生长幼苗的子叶积累高水平的原叶绿素酸酯还原酶mRNA；然而，在这些组织光照后，编码原叶绿素酸酯还原酶的mRNA稳态水平几乎没有变化。黑暗生长幼苗的茎组织不含显著水平的原叶绿素酸酯还原酶mRNA，而相同年龄的光照生长植物的茎积累了大量的该信息。这些结果表明光和组织的发育年龄影响松树中lpcr表达的调控。
