Galactolipid deficiency and abnormal chloroplast development in the Arabidopsis MGD synthase 1 mutant
Galactolipid deficiency and abnormal chloroplast development in the Arabidopsis MGD synthase 1 mutant
复制标题
DOI：
10.1073/pnas.100132197
复制
发表时间：
2000-07-05
影响因子：
11.1
通讯作者：
Chory, J
中科院分区：
文献类型：
--
作者：
Jarvis, P;Dörmann, P;Chory, J
脂质单半乳糖二酰甘油(MGD)是叶绿体光合膜的主要结构成分，它的形成是由MGD合成酶催化的，在许多植物中，MGD来自两种不同的生物合成途径：完全在叶绿体内操作的原核途径和涉及内质网步骤的真核途径。本文描述了一个含有MGD合成酶基因缺陷的拟南芥突变体(MGD1)的鉴定和鉴定。它具有黄绿色的表型，这与每株总叶绿素大约50%的缺乏有关。与野生型相比，MGD1基因转录起始点附近有1个T-DNA插入，MGD1mRNA丰度降低了75%。MGD1的稳定转录水平与MGD合酶活性之间的相关性(在MGd1中也降低了75%)表明MGD1是绿色组织中最重要的MGD合成酶。与野生型相比，突变体叶片中的MGD含量减少了42%。突变株MGD的16：3脂肪酸含量减少了23%，18：3脂肪酸含量增加了10%。由于16：3是原核途径中MGD的一个特征，因此MGD1可能在原核途径中具有一定的选择性。最后，MGD？与叶绿体超微结构的显著缺陷相关，强烈暗示了MGD在质膜结构组织中的独特作用。
The lipid monogalactosyl diacylglycerol (MGD) is a major structural component of photosynthetic membranes in chloroplasts, Its formation is catalyzed by the enzyme MGD synthase, In many plants, MGD derives from two different biosynthetic pathways: the prokaryotic pathway, which operates entirely within the plastid, and the eukaryotic pathway, which involves steps in the endoplasmic reticulum, Here, we describe the identification and characterization of an Arabidopsis mutant with a defective MGD synthase gene (MGD1), The mutant was identified in a screen of T-DNA lines for individuals with defects in chloroplast biogenesis. It has a yellow-green phenotype that correlates with a approximate to 50% deficiency in total chlorophyll per plant. A single T-DNA insertion is located adjacent to the transcription initiation site of the MGD1 gene, and the abundance of MGD1 mRNA is reduced by 75% compared with wild type. Correlation between steady-state MGD1 transcript levels and MGD synthase activity (also reduced by 75% in mgd1) suggests that MGD1 is the most important MGD synthase in green tissues. The amount of MGD in mutant leaves is reduced by 42% compared with wild type. MGD from the mutant contains 23% less 16:3 fatty acid and 10% more 18:3 fatty acid. Because 16:3 is a characteristic feature of MGD from the prokaryotic pathway, it is possible that MGD1 operates with some preference in the prokaryotic pathway. Finally, the MGD-deficiency of mgd? is correlated with striking defects in chloroplast ultrastructure, strongly suggesting a unique role for MGD in the structural organization of plastidic membranes.