Degree Programs in Life and Earth Sciences, University of Tsukuba, Tsukuba 305-8572, Japan.
Graduate School of Life and Environmental Sciences, University of Tsukuba, Tsukuba 305-8572, Japan.
Proc Natl Acad Sci U S A. 2024 Mar 5;121(10):e2318542121. doi: 10.1073/pnas.2318542121. Epub 2024 Feb 26.
Pyrenoids are microcompartments that are universally found in the photosynthetic plastids of various eukaryotic algae. They contain ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) and play a pivotal role in facilitating CO assimilation via CO-concentrating mechanisms (CCMs). Recent investigations involving model algae have revealed that pyrenoid-associated proteins participate in pyrenoid biogenesis and CCMs. However, these organisms represent only a small part of algal lineages, which limits our comprehensive understanding of the diversity and evolution of pyrenoid-based CCMs. Here we report a pyrenoid proteome of the chlorarachniophyte alga , which possesses complex plastids acquired through secondary endosymbiosis with green algae. Proteomic analysis using mass spectrometry resulted in the identification of 154 potential pyrenoid components. Subsequent localization experiments demonstrated the specific targeting of eight proteins to pyrenoids. These included a putative Rubisco-binding linker, carbonic anhydrase, membrane transporter, and uncharacterized GTPase proteins. Notably, most of these proteins were unique to this algal lineage. We suggest a plausible scenario in which pyrenoids in chlorarachniophytes have evolved independently, as their components are not inherited from green algal pyrenoids.
淀粉核是普遍存在于各种真核藻类光合质体中的微区室。它们含有核酮糖-1,5-二磷酸羧化酶/加氧酶(Rubisco),并通过 CO 浓缩机制(CCMs)在促进 CO 同化方面发挥关键作用。最近对模式藻类的研究表明,与淀粉核相关的蛋白质参与淀粉核的生物发生和 CCMs。然而,这些生物仅代表藻类谱系的一小部分,这限制了我们对基于淀粉核的 CCMs 的多样性和进化的全面理解。在这里,我们报告了一种拥有通过与绿藻二次内共生获得的复杂质体的绿藻门甲藻的淀粉核蛋白质组。使用质谱的蛋白质组学分析鉴定出了 154 种潜在的淀粉核成分。随后的定位实验表明,有 8 种蛋白质特异性靶向淀粉核。其中包括一个假定的 Rubisco 结合接头、碳酸酐酶、膜转运蛋白和未鉴定的 GTPase 蛋白。值得注意的是,这些蛋白质中的大多数都是该藻类谱系所特有的。我们提出了一个合理的情景,即甲藻的淀粉核是独立进化的,因为它们的成分不是从绿藻的淀粉核中遗传而来的。