Structural insights into the assembly and energy transfer of the Lhcb9-dependent photosystem I from moss Physcomitrium patens
Structural insights into the assembly and energy transfer of the Lhcb9-dependent photosystem I from moss Physcomitrium patens
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DOI：
10.1038/s41477-023-01463-4
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发表时间：
2023-07-20
期刊：
影响因子：
18
通讯作者：
Li，Mei
中科院分区：
文献类型：
--
作者：
Sun，Haiyu;Shang，Hui;Li，Mei
在植物和绿色藻类中，捕光复合物I和II（LHCI和LHCII）构成光系统I（PSI）的触角，从而有效地增加PSI核心的横截面。立碗藓（Physcomitriumpatens，P. patens）是一种陆生光合自养生物，起源于绿色藻类和陆生植物的共同祖先，在进化的早期就已经被广泛研究。最大的PSI形式（PpPSI-L）表现出一种独特的组织，既不存在于开花植物中，也不存在于藻类中。它的形成是由P.专利特异性LHC蛋白，Lhcb 9。虽然先前的研究已经揭示了PpPSI-L的整体结构，但其组装细节和不同PpPSI类型之间的关系仍不清楚。在这里，我们报告了PpPSI-L的高分辨率结构。我们鉴定了14个PSI核心亚基，一个Lhcb 9，一个磷酸化的LHCII三聚体和八个LHCI单体排列成两条带。我们的结构分析确定了Lhcb 9和磷酸化LHCII在稳定复合物中的重要作用。此外，我们的研究结果表明，PpPSI开关之间的不同类型，共享相同的模块。这一特性有助于在不同光照条件下动态调节PSI的捕光能力。
In plants and green algae, light-harvesting complexes I and II (LHCI and LHCII) constitute the antennae of photosystem I (PSI), thus effectively increasing the cross-section of the PSI core. The mossPhyscomitrium patens(P. patens) represents a well-studied primary land-dwelling photosynthetic autotroph branching from the common ancestor of green algae and land plants at the early stage of evolution.P. patenspossesses at least three types of PSI with different antenna sizes. The largest PSI form (PpPSI-L) exhibits a unique organization found neither in flowering plants nor in algae. Its formation is mediated by theP. patens-specific LHC protein, Lhcb9. While previous studies have revealed the overall architecture ofPpPSI-L, its assembly details and the relationship between differentPpPSI types remain unclear. Here we report the high-resolution structure ofPpPSI-L. We identified 14 PSI core subunits, one Lhcb9, one phosphorylated LHCII trimer and eight LHCI monomers arranged as two belts. Our structural analysis established the essential role of Lhcb9 and the phosphorylated LHCII in stabilizing the complex. In addition, our results suggest thatPpPSI switches between different types, which share identical modules. This feature may contribute to the dynamic adjustment of the light-harvesting capability of PSI under different light conditions.