Liebisch T, Başoglu M, Jäger S, Büchel C
Institute of Molecular Biosciences, Goethe University Frankfurt, Frankfurt, Germany.
Photosynthetica. 2023 Sep 5;61(4):425-431. doi: 10.32615/ps.2023.032. eCollection 2023.
Diatom thylakoids contain much higher amounts of sulfoquinovosyl diacylglycerol (SQDG) than vascular plants and the hypothesis was brought forward that this relates to their special thylakoid structure. To test this hypothesis we created knock-down mutants in that exhibited a decreased SQDG content per cell. Surprisingly, the ratio between the different lipid classes did not change, pointing to strict regulation of thylakoid lipid composition. The antenna proteins, fucoxanthin-chlorophyll proteins (FCP), were reduced and photosystem (PS) I compared to PSII was increased as judged from absorbance spectra. CD spectroscopy indicated a tighter packing of chromophores. The reduction in FCP might help to avoid diametral changes in excitation energy transfer. In contrast, the increase in PSI in the mutants might counteract the diminishment of the usually huge PSI antenna. No changes in thylakoid structure were observed since the stoichiometry between different lipid classes seems to be carefully balanced.
硅藻类囊体中硫代异鼠李糖基二酰基甘油（SQDG）的含量比维管植物高得多，因此有人提出这与它们特殊的类囊体结构有关。为了验证这一假设，我们在[具体内容缺失]中创建了基因敲除突变体，这些突变体细胞内的SQDG含量降低。令人惊讶的是，不同脂质类别之间的比例没有变化，这表明类囊体脂质组成受到严格调控。从吸收光谱判断，天线蛋白、岩藻黄质 - 叶绿素蛋白（FCP）减少，与光系统II相比，光系统I增加。圆二色光谱表明发色团堆积更紧密。FCP的减少可能有助于避免激发能量转移的巨大变化。相比之下，突变体中光系统I的增加可能抵消通常巨大的光系统I天线的减少。由于不同脂质类别之间的化学计量似乎得到了精心平衡，因此未观察到类囊体结构的变化。
