Center for Biological Resources and Informatics, Tokyo Institute of Technology, 4259-B65 Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Japan.
Prog Lipid Res. 2011 Jul;50(3):234-9. doi: 10.1016/j.plipres.2011.02.003. Epub 2011 Mar 1.
Higher-plant chloroplast membranes are composed primarily of four characteristic lipids, namely monogalactosyldiacylglycerol, digalactosyldiacylglycerol, sulfoquinovosyldiacylglycerol (SQDG), and phosphatidylglycerol. Among them, SQDG is the only sulfur-containing anionic glycerolipid and is the least prevalent component of photosynthetic membrane lipids. SQDG biosynthesis is mostly mediated by UDP-sulfoquinovose synthase (SQD1) and SQDG synthase (SQD2). Recently, another essential gene for SQDG synthesis, UGP3, was identified using transcriptome coexpression analysis and reverse genetics. UGP3 is a novel plastid UDP-glucose pyrophosphorylase that supplies UDP-glucose to SQD1 in plastids. In Arabidopsis, SQDG is dispensable under normal growth conditions but important in certain environments, particularly phosphate-depleted conditions. The function of SQDG under phosphate-limited growth conditions is highly correlated with the regulation of other plant glycerolipid biosyntheses. This review summarizes recent research defining the mechanism for SQDG biosynthesis and its biological function in higher plants, particularly under phosphate-starved conditions.
高等植物叶绿体膜主要由四种特征脂质组成，即单半乳糖二酰甘油、双半乳糖二酰甘油、磺基奎诺糖二酰甘油 (SQDG) 和磷脂酰甘油。其中，SQDG 是唯一含硫的阴离子甘油脂，也是光合膜脂质中最不常见的成分。SQDG 的生物合成主要由 UDP-磺基奎诺糖合酶 (SQD1) 和 SQDG 合酶 (SQD2) 介导。最近，通过转录组共表达分析和反向遗传学，发现了另一个 SQDG 合成的必需基因 UGP3。UGP3 是一种新型质体 UDP-葡萄糖焦磷酸化酶，为质体中的 SQD1 提供 UDP-葡萄糖。在拟南芥中，SQDG 在正常生长条件下不是必需的，但在某些环境中，特别是在缺磷条件下很重要。在磷限制生长条件下，SQDG 的功能与其他植物甘油脂生物合成的调节高度相关。本综述总结了最近关于 SQDG 生物合成及其在高等植物中的生物学功能的研究，特别是在缺磷条件下的研究。
