LCAA, a Novel Factor Required for Magnesium Protoporphyrin Monomethylester Cyclase Accumulation and Feedback Control of Aminolevulinic Acid Biosynthesis in Tobacco1[W][OA]
LCAA, a Novel Factor Required for Magnesium Protoporphyrin Monomethylester Cyclase Accumulation and Feedback Control of Aminolevulinic Acid Biosynthesis in Tobacco1[W][OA]
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LCAA，烟草中镁原卟啉单甲酯环化酶积累和氨基乙酰丙酸生物合成反馈控制所需的新因子1[W][OA]
作者：
C. Albus;Annabel Salinas;Olaf Czarnecki;S. Kahlau;Maxi Rothbart;Wolfram Thiele;W. Lein;R. Bock;B. Grimm;M. Schöttler
从筛选部分下调导致烟草（Nicotiana tabacum）中强烈叶绿素缺乏的基因中获得低叶绿素积累A（LCAA）反义植物。LCAA突变体在一个功能未知的质体定位蛋白中受到影响，该蛋白在蓝细菌和所有光合真核生物中是保守的。它们遭受急剧减少的捕光复合物（LHC）的内容，而每叶面积的所有其他光合复合物的积累受到的影响较小。由于LHC蛋白质的干扰积累可能归因于LHC生物合成本身的缺陷或叶绿素生物合成的瓶颈，因此测量了叶绿素合成速率和叶绿素合成中间体。LCAA反义植物积累镁（Mg）原卟啉单甲酯并且含有降低的原叶绿素水平和降低的CHL 27（Mg原卟啉单甲酯环化酶的亚基）含量。双分子荧光互补分析证实LCAA和CHL 27之间的直接相互作用。5-氨基乙酰丙酸合成速率增加，并与谷氨酰转移RNA还原酶含量增加相关。我们认为，LCAA编码的镁原卟啉单甲酯环化酶的一个额外的亚基，是所需的CHL 27的稳定性，并有助于反馈控制5-氨基乙酰丙酸生物合成，叶绿素生物合成的限速步骤。
Low Chlorophyll Accumulation A (LCAA) antisense plants were obtained from a screen for genes whose partial down-regulation results in a strong chlorophyll deficiency in tobacco (Nicotiana tabacum). The LCAA mutants are affected in a plastid-localized protein of unknown function, which is conserved in cyanobacteria and all photosynthetic eukaryotes. They suffer from drastically reduced light-harvesting complex (LHC) contents, while the accumulation of all other photosynthetic complexes per leaf area is less affected. As the disturbed accumulation of LHC proteins could be either attributable to a defect in LHC biogenesis itself or to a bottleneck in chlorophyll biosynthesis, chlorophyll synthesis rates and chlorophyll synthesis intermediates were measured. LCAA antisense plants accumulate magnesium (Mg) protoporphyrin monomethylester and contain reduced protochlorophyllide levels and a reduced content of CHL27, a subunit of the Mg protoporphyrin monomethylester cyclase. Bimolecular fluorescence complementation assays confirm a direct interaction between LCAA and CHL27. 5-Aminolevulinic acid synthesis rates are increased and correlate with an increased content of glutamyl-transfer RNA reductase. We suggest that LCAA encodes an additional subunit of the Mg protoporphyrin monomethylester cyclase, is required for the stability of CHL27, and contributes to feedback-control of 5-aminolevulinic acid biosynthesis, the rate-limiting step of chlorophyll biosynthesis.
影响因子：
11.6
作者：
Schult, Kerstin;Meierhoff, Karin;Westhoff, Peter
通讯作者：
Westhoff, Peter