Light-independent chlorophyll biosynthesis: involvement of the chloroplast gene chlL (frxC).
Light-independent chlorophyll biosynthesis: involvement of the chloroplast gene chlL (frxC).
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不依赖光的叶绿素生物合成：叶绿体基因 chlL (frxC) 的参与。
DOI：
10.1105/tpc.4.8.929
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发表时间：
1992
期刊：
影响因子：
--
通讯作者：
Bauer,CE
中科院分区：
文献类型：
--
作者：
Suzuki,JY;Bauer,CE
莱茵衣藻叶绿体基因 chlL (frxC) 被证明参与原叶绿素内酯到叶绿素内酯的光独立转化。 ChlL 编码的多肽与光合细菌荚膜红杆菌中的细菌叶绿素 (bch) 生物合成 bchL 基因产物具有惊人的 53% 氨基酸序列同一性。在之前的分析中，我们证明 bchL 参与光独立的原叶绿素内酯还原，从而暗示 chlL 参与光合真核生物中光独立的原叶绿素内酯还原。为了对 ChlL 进行功能/突变分析，我们利用粒子枪介导的转化来破坏 ChlL 在衣藻叶绿体基因组中内源基因座的结构序列。多拷贝叶绿体基因组对于被破坏的chlL等位基因是同质的转化体表现出“暗中黄色”表型，我们证明这是原叶绿素在黑暗中积累的结果。交叉杂交分析也证明了远缘细菌和不开花的陆地植物中存在 chlL 同源物，这些细菌和不开花的陆地植物被认为能够在黑暗中合成叶绿素。相比之下，我们没有观察到 chlL 探针与来自需要光合成叶绿素的代表性被子植物的 DNA 样品的交叉杂交，这支持了我们的结论，即 chlL 参与了不依赖于光的叶绿素生物合成。讨论了 chlL 在原叶绿素内酯还原中的作用，以及光非依赖性和光依赖性原叶绿素内酯还原酶可能源自细菌的最新证据。
The Chlamydomonas reinhardtii chloroplast gene chlL (frxC) is shown to be involved in the light-independent conversion of protochlorophyllide to chlorophyllide. The polypeptide encoded by chlL contains a striking 53% amino acid sequence identity with the bacteriochlorophyll (bch) biosynthesis bchL gene product in the photosynthetic bacterium Rhodobacter capsulatus. In a previous analysis, we demonstrated that bchL was involved in light-independent protochlorophyllide reduction, thereby implicating chlL in light-independent protochlorophyllide reduction in photosynthetic eukaryotes. To perform a functional/mutational analysis of chlL, we utilized particle gun-mediated transformation to disrupt the structural sequence of chlL at its endogenous locus in the chloroplast genome of Chlamydomonas. Transformants for which the multicopy chloroplast genome was homoplasmic for the disrupted chlL allele exhibit a "yellow-in-the-dark" phenotype that we demonstrated to be a result of the dark accumulation of protochlorophyllide. The presence of a chlL homolog in distantly related bacteria and nonflowering land plants, which are thought to be capable of synthesizing chlorophyll in the dark, was also demonstrated by cross-hybridization analysis. In contrast, we observed no cross-hybridization of a probe of chlL to DNA samples from representative angiosperms that require light for chlorophyll synthesis, in support of our conclusion that chlL is involved in light-independent chlorophyll biosynthesis. The role of chlL in protochlorophyllide reduction as well as recent evidence that both light-independent and light-dependent protochlorophyllide reductases may be of bacterial origin are discussed.