1
|
Liu S, Chen Y, Du T, Zhao W, Liu X, Zhang H, Yuan Q, Gao L, Dong Y, Gao X, Gong Y, Cao P. A dimer-monomer transition captured by the crystal structures of cyanobacterial apo flavodoxin. Biochem Biophys Res Commun 2023; 639:134-141. [PMID: 36493556 DOI: 10.1016/j.bbrc.2022.11.089] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Accepted: 11/27/2022] [Indexed: 11/30/2022]
Abstract
In cyanobacteria and algae (but not plants), flavodoxin (Fld) replaces ferredoxin (Fd) under stress conditions to transfer electrons from photosystem I (PSI) to ferredoxin-NADP+ reductase (FNR) during photosynthesis. Fld constitutes a small electron carrier noncovalently bound to flavin mononucleotide (FMN), and also an ideal model for revealing the protein/flavin-binding mechanism because of its relative simplicity compared to other flavoproteins. Here, we report two crystal structures of apo-Fld from Synechococcus sp. PCC 7942, one dimeric structure of 2.09 Å and one monomeric structure of 1.84 Å resolution. Analytical ultracentrifugation showed that in solution, apo-Fld exists both as monomers and dimers. Our dimer structure contains two ligand-binding pockets separated by a distance of 45 Å, much longer than the previous structures of FMN-bound dimers. These results suggested a potential dimer-monomer transition mechanism of cyanobacterial apo-Fld. We further propose that the dimer represents the "standby" state to stabilize itself, while the monomer constitutes the "ready" state to bind FMN. Furthermore, we generated a new docking model of cyanobacterial Fld-FNR complex based on the recently reported cryo-EM structures, and mapped the special interactions between Fld and FNR in detail.
Collapse
Affiliation(s)
- Shuwen Liu
- Faculty of Environment and Life, Beijing University of Technology, 100 Pingleyuan, Chaoyang District, Beijing, 100124, China
| | - Yuanyuan Chen
- The Research Platform for Protein Sciences, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing, 100101, China
| | - Tianming Du
- Faculty of Environment and Life, Beijing University of Technology, 100 Pingleyuan, Chaoyang District, Beijing, 100124, China
| | - Wencong Zhao
- Faculty of Environment and Life, Beijing University of Technology, 100 Pingleyuan, Chaoyang District, Beijing, 100124, China
| | - Xuejing Liu
- Faculty of Environment and Life, Beijing University of Technology, 100 Pingleyuan, Chaoyang District, Beijing, 100124, China
| | - Heng Zhang
- Center for Multidisciplinary Research, Institute of High Energy Physics, Chinese Academy of Sciences, 19B YuquanLu, Shijingshan District, Beijing, 100049, China
| | - Qing Yuan
- Faculty of Environment and Life, Beijing University of Technology, 100 Pingleyuan, Chaoyang District, Beijing, 100124, China
| | - Liang Gao
- Faculty of Environment and Life, Beijing University of Technology, 100 Pingleyuan, Chaoyang District, Beijing, 100124, China
| | - Yuhui Dong
- Center for Multidisciplinary Research, Institute of High Energy Physics, Chinese Academy of Sciences, 19B YuquanLu, Shijingshan District, Beijing, 100049, China
| | - Xueyun Gao
- Faculty of Environment and Life, Beijing University of Technology, 100 Pingleyuan, Chaoyang District, Beijing, 100124, China.
| | - Yong Gong
- Center for Multidisciplinary Research, Institute of High Energy Physics, Chinese Academy of Sciences, 19B YuquanLu, Shijingshan District, Beijing, 100049, China.
| | - Peng Cao
- Faculty of Environment and Life, Beijing University of Technology, 100 Pingleyuan, Chaoyang District, Beijing, 100124, China.
| |
Collapse
|