生物合成
生物
叶绿素
四吡咯
原叶绿素
叶绿素a
突变体
作者
Weiqing Zhang,Robert D. Willows,Rui Deng,Zheng Li,Mengqi Li,Yan Wang,Yunling Guo,Weida Shi,Qiuling Fan,Shelley S. Martin,Nathan C. Rockwell,J. Clark Lagarias,Deqiang Duanmu
标识
DOI:10.1073/pnas.2104443118
摘要
Biosyntheses of chlorophyll and heme in oxygenic phototrophs share a common trunk pathway that diverges with insertion of magnesium or iron into the last common intermediate, protoporphyrin IX. Since both tetrapyrroles are pro-oxidants, it is essential that their metabolism is tightly regulated. Here, we establish that heme-derived linear tetrapyrroles (bilins) function to stimulate the enzymatic activity of magnesium chelatase (MgCh) via their interaction with GENOMES UNCOUPLED 4 (GUN4) in the model green alga Chlamydomonas reinhardtii. A key tetrapyrrole-binding component of MgCh found in all oxygenic photosynthetic species, CrGUN4, also stabilizes the bilin-dependent accumulation of protoporphyrin IX-binding CrCHLH1 subunit of MgCh in light-grown C. reinhardtii cells by preventing its photooxidative inactivation. Exogenous application of biliverdin IXα reverses the loss of CrCHLH1 in the bilin-deficient heme oxygenase (hmox1) mutant, but not in the gun4 mutant. We propose that these dual regulatory roles of GUN4:bilin complexes are responsible for the retention of bilin biosynthesis in all photosynthetic eukaryotes, which sustains chlorophyll biosynthesis in an illuminated oxic environment.
科研通智能强力驱动
Strongly Powered by AbleSci AI