The major light-harvesting system in cyanobacteria, the phycobilisome, is an essential component of the photosynthetic apparatus that regulates the utilization of the natural light source—the Sun. Earlier works revealed that the thylakoid membrane composition and its physical properties might have an important role in antennas docking. Polyunsaturated lipids and xanthophylls are among the most significant modulators of the physical properties of thylakoid membranes. In the nature, the action of these molecules is orchestrated in response to environmental stimuli among which the growth temperature is the most influential. In order to further clarify the significance of thylakoid membrane physical properties for the phycobilisomes assembly (i.e. structural integrity) and their ability to efficiently direct the excitation energy towards the photosynthetic complexes, in this work, we utilize cyanobacterial Synechocystis sp. PCC 6803 mutants deficient in polyunsaturated lipids (AD mutant) and xanthophylls (RO mutant), as well as a strain depleted of both xanthophylls and polyunsaturated lipids (ROAD multiple mutant). For the first time, we discuss the effect of those mutations on the phycobilisomes assembly, integrity and functionality at optimal (30 °C) and moderate low (25 °C) and high (35 °C) temperatures. Our results show that xanthophyll depletion exerts a much stronger effect on both phycobilisome’s integrity and the response of cells to growth at suboptimal temperatures than lipid unsaturation level. The strongest effects were observed for the combined ROAD mutant, which exhibited thermally destabilized phycobilisomes and a population of energetically uncoupled phycocyanin units.

蓝藻中的主要集光系统，藻胆体，是调节自然光源（太阳）利用率的光合作用设备的重要组成部分。早期的工作表明类囊体膜的组成及其物理性质可能在天线对接中起重要作用。多不饱和脂质和叶黄素是类囊体膜物理特性的最重要调节剂。在自然界中，这些分子的作用是响应环境刺激而协调进行的，其中生长温度最有影响。为了进一步阐明类囊体膜物理特性对藻胆体组装的重要性（即集胞藻 PCC 6803突变体缺乏多不饱和脂质（AD突变体）和叶黄素（RO突变体），以及缺乏叶黄素和多不饱和脂质的菌株（ROAD多重突变体）。首次，我们讨论了这些突变在最佳温度（30°C）和中度低温（25°C）和高温（35°C）下对藻胆体组装，完整性和功能的影响。我们的结果表明，叶绿素的消耗对藻胆体的完整性和细胞在低于最佳温度下对生长的响应均比脂质不饱和水平强得多。对于组合的ROAD突变体，观察到最强的作用，该突变体表现出热不稳定的藻胆体和大量能量上未偶联的藻蓝蛋白单位。