Department of Biology, University of York, York YO10 5DD, UK; Centre for Novel Agricultural Products, Department of Biology, University of York, York YO10 5DD, UK.
Biozentrum, University of Basel, Spitalstrasse 41, 4056 Basel, Switzerland.
Cell. 2024 Oct 17;187(21):5935-5950.e18. doi: 10.1016/j.cell.2024.09.025. Epub 2024 Oct 4.
Diatoms are central to the global carbon cycle. At the heart of diatom carbon fixation is an overlooked organelle called the pyrenoid, where concentrated CO is delivered to densely packed Rubisco. Diatom pyrenoids fix approximately one-fifth of global CO, but the protein composition of this organelle is largely unknown. Using fluorescence protein tagging and affinity purification-mass spectrometry, we generate a high-confidence spatially defined protein-protein interaction network for the diatom pyrenoid. Within our pyrenoid interaction network are 10 proteins with previously unknown functions. We show that six of these form a shell that encapsulates the Rubisco matrix and is critical for pyrenoid structural integrity, shape, and function. Although not conserved at a sequence or structural level, the diatom pyrenoid shares some architectural similarities to prokaryotic carboxysomes. Collectively, our results support the convergent evolution of pyrenoids across the two main plastid lineages and uncover a major structural and functional component of global CO fixation.
硅藻在全球碳循环中起着核心作用。硅藻碳固定的核心是一个被忽视的细胞器，称为淀粉核，在这里浓缩的 CO 被输送到密集排列的 Rubisco。硅藻淀粉核固定了全球约五分之一的 CO，但这个细胞器的蛋白质组成在很大程度上是未知的。使用荧光蛋白标记和亲和纯化-质谱法，我们生成了硅藻淀粉核的高可信度空间定义的蛋白质-蛋白质相互作用网络。在我们的淀粉核相互作用网络中，有 10 种具有先前未知功能的蛋白质。我们表明，其中 6 种形成了一个壳，包裹着 Rubisco 基质，对于淀粉核的结构完整性、形状和功能至关重要。虽然在序列或结构水平上没有保守性，但硅藻淀粉核与原核羧化体在结构上有一些相似之处。总的来说，我们的结果支持了淀粉核在两个主要质体谱系中的趋同进化，并揭示了全球 CO 固定的一个主要结构和功能组成部分。
