Biology Department, Brookhaven National Laboratory, Upton, NY, USA.
Plant Signal Behav. 2011 Mar;6(3):458-60. doi: 10.4161/psb.6.3.14715. Epub 2011 Mar 1.
The biogenesis of photosynthetic membranes in plants relies largely on lipid import from the endoplasmic reticulum (ER) and this lipid transport process is mediated by TGD proteins in Arabidopsis. Such a dependency of chloroplast biogenesis on ER-to-plastid lipid transport was recently exemplified by analyzing double mutants between tgd1-1 or tgd4-3 and fad6 mutants. The fad6 mutants are defective in the desaturation of membrane lipids in chloroplasts and therefore dependent on import of polyunsaturated lipid precursors from the ER for constructing a competent thylakoid membrane system. In support of a critical role of TGD proteins in ER-to-plastid lipid trafficking, we showed that the introduction of the tgd mutations into fad6 mutant backgrounds led to drastic reductions in relative amounts of thylakoid lipids. Moreover, the tgd1-1 fad6 and tgd4-3 fad6 double mutants were deficient in polyunsaturated fatty acids in chloroplast membrane lipids, and severely compromised in the biogenesis of photosynthetic membrane systems. Here we report that these double mutants are severely impaired in chloroplast division. The possible role of membrane lipids in chloroplast division is discussed. :
植物光合膜的生物发生在很大程度上依赖于内质网 (ER) 的脂质导入，而这种脂质转运过程是由拟南芥中的 TGD 蛋白介导的。最近，通过分析 tgd1-1 或 tgd4-3 与 fad6 突变体的双突变体，证明了叶绿体生物发生对 ER 到质体脂质转运的依赖性。fad6 突变体在叶绿体膜脂质的去饱和作用中存在缺陷，因此依赖于从 ER 导入多不饱和脂质前体来构建有能力的类囊体膜系统。为了支持 TGD 蛋白在 ER 到质体脂质运输中的关键作用，我们表明，将 tgd 突变引入 fad6 突变体背景中会导致类囊体脂质的相对含量急剧减少。此外，tgd1-1 fad6 和 tgd4-3 fad6 双突变体在叶绿体膜脂质中缺乏多不饱和脂肪酸，并且在光合膜系统的生物发生中受到严重损害。在这里，我们报告这些双突变体在叶绿体分裂中受到严重损害。讨论了膜脂质在叶绿体分裂中的可能作用。
