Liu Helen W, Khera Radhika, Grob Patricia, Gallaher Sean D, Purvine Samuel O, Nicora Carrie D, Lipton Mary S, Niyogi Krishna K, Nogales Eva, Iwai Masakazu, Merchant Sabeeha S
Department of Plant and Microbial Biology, University of California, Berkeley, CA 94720, USA.
Howard Hughes Medical Institute, University of California, Berkeley, CA 94720, USA.
bioRxiv. 2024 Dec 12:2024.12.11.624522. doi: 10.1101/2024.12.11.624522.
Iron (Fe) availability limits photosynthesis at a global scale where Fe-rich photosystem (PS) I abundance is drastically reduced in Fe-poor environments. We used single-particle cryo-electron microscopy to reveal a unique Fe starvation-dependent arrangement of light-harvesting chlorophyll (LHC) proteins where Fe starvation-induced TIDI1 is found in an additional tetramer of LHC proteins associated with PSI in and . These cosmopolitan green algae are resilient to poor Fe nutrition. TIDI1 is a distinct LHC protein that co-occurs in diverse algae with flavodoxin (an Fe-independent replacement for the Fe-containing ferredoxin). The antenna expansion in eukaryotic algae we describe here is reminiscent of the iron-starvation induced (-encoding) antenna ring in cyanobacteria, which typically co-occurs with , encoding flavodoxin. Our work showcases the convergent strategies that evolved after the Great Oxidation Event to maintain PSI capacity.
在全球范围内，铁（Fe）的可利用性限制了光合作用，在铁缺乏的环境中，富含铁的光系统（PS）I的丰度会急剧降低。我们使用单颗粒冷冻电子显微镜揭示了光捕获叶绿素（LHC）蛋白独特的铁饥饿依赖性排列，在[具体文献]中，铁饥饿诱导的TIDI1存在于与PS I相关的LHC蛋白的额外四聚体中。这些广泛分布的绿藻对铁营养缺乏具有耐受性。TIDI1是一种独特的LHC蛋白，与黄素氧还蛋白（含铁铁氧还蛋白的铁独立替代物）共同存在于多种藻类中。我们在此描述的真核藻类中的天线扩展让人联想到蓝细菌中铁饥饿诱导的（编码）天线环，它通常与编码黄素氧还蛋白的[相关基因]共同出现。我们的工作展示了大氧化事件后为维持PS I能力而进化出的趋同策略。
