Ivanov Alexander G, Hendrickson Luke, Krol Marianna, Selstam Eva, Oquist Gunnar, Hurry Vaughan, Huner Norman P A
Department of Biology and The Biotron, University of Western Ontario, London, Ontario, Canada.
Plant Cell Physiol. 2006 Aug;47(8):1146-57. doi: 10.1093/pcp/pcj089. Epub 2006 Jul 18.
Compared with wild type, the dgd1 mutant of Arabidopsis thaliana exhibited a lower amount of PSI-related Chl-protein complexes and lower abundance of the PSI-associated polypeptides, PsaA, PsaB, PsaC, PsaL and PsaH, with no changes in the levels of Lhca1-4. Functionally, the dgd1 mutant exhibited a significantly lower light-dependent, steady-state oxidation level of P700 (P700(+)) in vivo, a higher intersystem electron pool size, restricted linear electron transport and a higher rate of reduction of P700(+) in the dark, indicating an increased capacity for PSI cyclic electron transfer compared with the wild type. Concomitantly, the dgd1 mutant exhibited a higher sensitivity to and incomplete recovery of photoinhibition of PSI. Furthermore, dgd1 exhibited a lower capacity to undergo state transitions compared with the wild type, which was associated with a higher reduction state of the plastoquinone (PQ) pool. We conclude that digalactosyl-diacylglycerol (DGDG) deficiency results in PSI acceptor-side limitations that alter the flux of electrons through the photosynthetic electron chain and impair the regulation of distribution of excitation energy between the photosystems. These results are discussed in terms of thylakoid membrane domain reorganization in response to DGDG deficiency in A. thaliana.
与野生型相比，拟南芥的dgd1突变体表现出较低量的与光系统I（PSI）相关的叶绿素蛋白复合物，以及PSI相关多肽PsaA、PsaB、PsaC、PsaL和PsaH的丰度较低，而Lhca1 - 4的水平没有变化。在功能上，dgd1突变体在体内表现出显著较低的光依赖型、稳态的P700氧化水平（P700(+)），较大的电子传递链间电子库大小，受限的线性电子传递以及在黑暗中较高的P700(+)还原速率，表明与野生型相比，PSI循环电子传递能力增强。同时，dgd1突变体对PSI光抑制表现出更高的敏感性且光抑制恢复不完全。此外，与野生型相比，dgd1进行状态转换的能力较低，这与质体醌（PQ）库的较高还原状态相关。我们得出结论，二半乳糖基二酰基甘油（DGDG）缺乏导致PSI受体侧限制，改变了通过光合电子链传递的电子通量，并损害了光系统之间激发能分配的调节。这些结果将根据拟南芥中响应DGDG缺乏的类囊体膜结构域重组进行讨论。
