Biostructural Mechanism Laboratory, RIKEN SPring-8 Center, Sayo, Hyogo, Japan.
Research Center for Artificial Photosynthesis (ReCAP), Osaka City University, Sumiyoshi-ku, Osaka, Japan.
Nat Commun. 2021 Apr 20;12(1):2333. doi: 10.1038/s41467-021-22502-8.
Acaryochloris marina is one of the cyanobacterial species that can use far-red light to drive photochemical reactions for oxygenic photosynthesis. Here, we report the structure of A. marina photosystem I (PSI) reaction center, determined by cryo-electron microscopy at 2.58 Å resolution. The structure reveals an arrangement of electron carriers and light-harvesting pigments distinct from other type I reaction centers. The paired chlorophyll, or special pair (also referred to as P740 in this case), is a dimer of chlorophyll d and its epimer chlorophyll d'. The primary electron acceptor is pheophytin a, a metal-less chlorin. We show the architecture of this PSI reaction center is composed of 11 subunits and we identify key components that help explain how the low energy yield from far-red light is efficiently utilized for driving oxygenic photosynthesis.
海洋聚球藻是一种能够利用远红光进行光化学反应的蓝细菌物种，从而进行产氧光合作用。在这里，我们报告了海洋聚球藻光系统 I（PSI）反应中心的结构，该结构通过冷冻电子显微镜在 2.58 Å 的分辨率下确定。该结构揭示了电子载体和光捕获色素的排列与其他 I 型反应中心明显不同。成对的叶绿素或特殊对（在这种情况下也称为 P740）是叶绿素 d 和其差向异构体叶绿素 d'的二聚体。初级电子受体是脱镁叶绿酸 a，一种无金属的叶绿素。我们展示了这种 PSI 反应中心的结构由 11 个亚基组成，并确定了关键组件，这些组件有助于解释如何有效地利用远红光的低能量产率来驱动产氧光合作用。
