Ternary protein complex of ferredoxin, ferredoxin:thioredoxin reductase, and thioredoxin studied by paramagnetic NMR spectroscopy

Xingfu Xu, Peter Schürmann, Jung Sung Chung, Mathias A.S. Hass, Sung Kun Kim, Masakazu Hirasawa, Jatindra N. Tripathy, David B. Knaff, Marcellus Ubbink

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

In oxygenic photosynthetic cells, carbon metabolism is regulated by a light-dependent redox signaling pathway through which the light signal is transmitted in the form of electrons via a redox chain comprising ferredoxin (Fd), ferredoxin:thioredoxin reductase (FTR), and thioredoxin (Trx). Trx affects the activity of a variety of enzymes via dithiol oxidation and reduction reactions. FTR reduces an intramolecular disulfide bridge of Trx, and Trx reduction involves a transient cross-link with FTR. NMR spectroscopy was used to investigate the interaction of Fd, FTR, and an m-type Trx. NMR titration experiments indicate that FTR uses distinct sites to bind Fd and Trx simultaneously to form a noncovalent ternary complex. The orientation of Trx-m relative to FTR was determined from the intermolecular paramagnetic broadening caused by the [4Fe-4S] cluster of FTR. Two models of the noncovalent binary complex of FTR/Trx-m based on the paramagnetic distance restraints were obtained. The models suggest that either a modest or major rotational movement of Trx must take place when the noncovalent binary complex proceeds to the covalent complex. This study demonstrates the complementarity of paramagnetic NMR and X-ray diffraction of crystals in the elucidation of dynamics in a transient protein complex.

Original languageEnglish
Pages (from-to)17576-17582
Number of pages7
JournalJournal of the American Chemical Society
Volume131
Issue number48
DOIs
StatePublished - Dec 9 2009

Fingerprint Dive into the research topics of 'Ternary protein complex of ferredoxin, ferredoxin:thioredoxin reductase, and thioredoxin studied by paramagnetic NMR spectroscopy'. Together they form a unique fingerprint.

Cite this