Kunst L, Browse J, Somerville C
MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824.
Plant Physiol. 1989 Jul;90(3):846-53. doi: 10.1104/pp.90.3.846.
Mutants of Arabidopsis thaliana deficient in plastid glycerol-3-phosphate acyltransferase activity have altered chloroplast membrane lipid composition. This caused an increase in the number of regions of appressed membrane per chloroplast and a decrease in the average number of thylakoid membranes in the appressed regions. The net effect was a significant decrease in the ratio of appressed to nonappressed membranes. A comparison of 77 K fluorescence emission spectra of thylakoid membranes from the mutant and wild type indicated that the ultrastructural changes were associated with an altered distribution of excitation energy transfer from antenna chlorophyll to photosystem II and photosystem I in the mutant. The changes in leaf lipid composition did not significantly affect growth or development of the mutant under standard conditions. However, at temperatures above 28 degrees C the mutant grew slightly more rapidly than the wild type, and measurements of temperature-induced fluorescence yield enhancement suggested an increased thermal stability of the photosynthetic apparatus of the mutant. These effects are consistent with other evidence suggesting that membrane lipid composition is an important determinant of chloroplast structure but has relatively minor direct effects on the function of the membrane proteins associated with photosynthetic electron transport.
缺乏质体甘油-3-磷酸酰基转移酶活性的拟南芥突变体，其叶绿体膜脂成分发生了改变。这导致每个叶绿体中紧密堆积膜区域的数量增加，以及紧密堆积区域内类囊体膜的平均数量减少。最终结果是紧密堆积膜与非紧密堆积膜的比例显著降低。对突变体和野生型类囊体膜的77K荧光发射光谱进行比较表明，超微结构的变化与突变体中激发能从天线叶绿素向光系统II和光系统I转移的分布改变有关。在标准条件下，叶片脂质成分的变化对突变体的生长或发育没有显著影响。然而，在高于28摄氏度的温度下，突变体的生长速度比野生型略快，并且温度诱导荧光产量增强的测量表明突变体光合装置的热稳定性增加。这些效应与其他证据一致，表明膜脂成分是叶绿体结构的重要决定因素，但对与光合电子传递相关的膜蛋白功能的直接影响相对较小。
