Deacylation of galactolipids decomposes photosystem II dimers to enhance degradation of damaged D1 protein
Deacylation of galactolipids decomposes photosystem II dimers to enhance degradation of damaged D1 protein
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DOI：
10.1093/plphys/kiac460
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发表时间：
2022-10-03
期刊：
影响因子：
7.4
通讯作者：
Wada, Hajime
中科院分区：
文献类型：
--
作者：
Jimbo, Haruhiko;Wada, Hajime
光系统II（PSII）含有许多脂质分子，这些分子对于PSII的功能和维持是必不可少的。在强光条件下，PSII复合物在修复过程中被动态修饰;然而，PSII结构动态变化的分子机制仍不清楚。在本研究中，我们研究了脂肪酶在修复PSII在集胞藻PCC 6803的作用。我们确定了由sll 1969基因编码的蛋白质，以前命名为脂肪酶A（利帕），在集胞藻属PCC 6803基因组中作为参与PSII修复的脂肪酶的候选者。在大肠杆菌细胞中表达的重组蛋白水解单半乳糖基二酰基甘油（MGDG）和双半乳糖基二酰基甘油以及与硬脂酸酯化的三酰基甘油的sn-1位的脂肪酸。在破坏突变体的利帕基因的PSII修复受到抑制的破坏D1蛋白在强光下的缓慢降解。在强光下，利帕突变体细胞中PSII二聚体的水平高于野生型（WT）细胞。利帕蛋白在体内与PSII二聚体结合，重组利帕蛋白通过减少PSII复合物中的MGDG含量将从WT细胞纯化的PSII二聚体分解为单体。这些结果表明，利帕与PSII二聚体反应，通过消化MGDG将其解离成单体，促进了PSII修复过程中D1的降解;脂肪酶可能在光系统II（PSII）二聚体的界面上使半乳糖脂脱酰，并诱导二聚体解体，从而加速了PSII的蛋白降解和修复。
Photosystem II (PSII) contains many lipid molecules that are essential for the function and maintenance of PSII. Under strong light conditions, PSII complexes are dynamically modified during the repair process; however, the molecular mechanism of the dynamic changes in the PSII structure is still unclear. In the present study, we investigated the role of a lipase in the repair of PSII in Synechocystis sp. PCC 6803. We identified a protein encoded by the sll1969 gene, previously named lipase A (lipA), in the Synechocystis sp. PCC 6803 genome as a candidate for the lipase involved in PSII repair. Recombinant protein expressed in Escherichia coli cells hydrolyzed fatty acids at the sn-1 position of monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol as well as triacylglycerol esterified with stearic acids. PSII repair in a disrupted mutant of the lipA gene was suppressed by the slow degradation of damaged D1 protein under strong light. The level of the PSII dimer remained higher in lipA mutant cells than wild-type (WT) cells under strong light. LipA protein was associated with the PSII dimer in vivo, and recombinant LipA protein decomposed PSII dimers purified from WT cells to monomers by reducing MGDG content in the PSII complex. These results indicate that LipA reacts with PSII dimers, dissociates them into monomers by digesting MGDG, and enhances D1 degradation during PSII repair.A lipase deacylates galactolipids presumably at the interface of photosystem II (PSII) dimer and induces the disassembly of the dimer that accelerates the protein degradation and repair of PSII.