Hölzl Georg, Dörmann Peter
Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany.
Prog Lipid Res. 2007 Sep;46(5):225-43. doi: 10.1016/j.plipres.2007.05.001. Epub 2007 May 21.
Phosphoglycerolipids are abundant membrane constituents in prokaryotic and eukaryotic cells. However, glycoglycerolipids are the predominant lipids in chloroplasts of plants and eukaryotic algae and in cyanobacteria. Membrane composition in chloroplasts and cyanobacteria is highly conserved, with monogalactosyldiacylglycerol (MGD) and digalactosyldiacylglycerol (DGD) representing the most abundant lipids. The genes encoding enzymes of galactolipid biosynthesis have been isolated from Arabidopsis. Galactolipids are crucial for growth under normal and phosphate limiting conditions. Furthermore, they are indispensable for maximal efficiency of photosynthesis. A wide variety of glycoglycerolipids is found in different bacteria. These lipids contain glucose or galactose, in some cases also mannose or other sugars with different glycosidic linkages in their head group. Some bacterial species produce unusual glycoglycerolipids, such as glycophospholipids or glycoglycerolipids carrying sugar head groups esterified with acyl residues. A number of genes coding for bacterial glycoglycerolipid synthases have been cloned and the enzymes characterized. In contrast to the breadth of information available on their structural diversity, much less is known about functional aspects of bacterial glycoglycerolipids. In some bacteria, glycoglycerolipids are required for membrane bilayer stability, they serve as precursors for the formation of complex membrane components, or they are crucial to support anoxygenic photosynthesis or growth during phosphate deficiency.
磷酸甘油酯是原核细胞和真核细胞中丰富的膜成分。然而，糖脂是植物、真核藻类叶绿体以及蓝细菌中的主要脂质。叶绿体和蓝细菌中的膜组成高度保守，单半乳糖基二酰甘油（MGD）和双半乳糖基二酰甘油（DGD）是最丰富的脂质。已从拟南芥中分离出编码半乳糖脂生物合成酶的基因。半乳糖脂对于正常和磷限制条件下的生长至关重要。此外，它们对于光合作用的最大效率是不可或缺的。在不同细菌中发现了各种各样的糖脂。这些脂质在其头部基团中含有葡萄糖或半乳糖，在某些情况下还含有甘露糖或其他具有不同糖苷键的糖。一些细菌物种产生不寻常的糖脂，例如糖磷脂或带有被酰基残基酯化的糖头部基团的糖脂。已经克隆了许多编码细菌糖脂合成酶的基因并对这些酶进行了表征。与关于其结构多样性的丰富信息相比，关于细菌糖脂功能方面的了解要少得多。在一些细菌中，糖脂对于膜双层稳定性是必需的，它们作为复杂膜成分形成的前体，或者对于支持无氧光合作用或磷缺乏期间的生长至关重要。
