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.
HHMI, University of California, Berkeley, CA 94720.
Proc Natl Acad Sci U S A. 2025 Jun 24;122(25):e2500621122. doi: 10.1073/pnas.2500621122. Epub 2025 Jun 16.
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 cryoelectron 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来揭示光捕获叶绿素（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PSI相关的LHC蛋白的另一个四聚体中。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，在多种藻类中与黄素氧还蛋白（一种不含铁的含铁铁氧还蛋白替代物）共同出现。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，其通常与编码黄素氧还蛋白的[具体基因]共同出现。我们的工作展示了大氧化事件后进化出的维持PSI能力的趋同策略。
