7C2B

Structural basis for thioredoxin isoform-based fine-tuning of ferredoxin-thioredoxin reductase activity.

(2020) Protein Sci 29: 2538-2545

• PubMed: 33015914 Search on PubMedSearch on PubMed Central
• DOI: https://doi.org/10.1002/pro.3964
• Primary Citation of Related Structures:  
  7BZK, 7C2B, 7C3F, 7C65


• PubMed Abstract: 
  

  Photosynthetic electron transport occurs on the thylakoid membrane of chloroplasts. Ferredoxin (Fd), the final acceptor in the electron transport chain, distributes electrons to several Fd-dependent enzymes including Fd-thioredoxin reductase (FTR). A cascade from Fd to FTR further reduces Thioredoxin (Trx), which tunes the activity of target metabolic enzymes eventually in a light-dependent manner. We previously reported that 10 Trx isoforms in Arabidopsis thaliana can be clustered into three classes based on the kinetics of the FTR-dependent reduction (high-, middle-, and low-efficiency classes). In this study, we determined the X-ray structure of three electron transfer complexes of FTR and Trx isoform, Trx-y1, Trx-f2, and Trx-m2, as representative examples of each class. Superposition of the FTR structure with/without Trx showed no main chain structural changes upon complex formation. There was no significant conformational change for single and complexed Trx-m structures. Nonetheless, the interface of FTR:Trx complexes displayed significant variation. Comparative analysis of the three structures showed two types of intermolecular interactions; (i) common interactions shared by all three complexes and (ii) isoform-specific interactions, which might be important for fine-tuning FTR:Trx activity. Differential electrostatic potentials of Trx isoforms may be key to isoform-specific interactions.

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Organizational Affiliation: 

Institute for Protein Research, Osaka University, Suita, Osaka, Japan.