X-ray dose-dependent structural changes of the [2Fe-2S] ferredoxin from Chlamydomonas reinhardtii. (13th April 2020)

• Record Type: Journal Article
• Authors: Ohnishi, Yusuke; Muraki, Norifumi; Kiyota, Daiki; Okumura, Hideo; Baba, Seiki; Kawano, Yoshiaki; Kumasaka, Takashi; Tanaka, Hideaki; Kurisu, Genji
• Is Part Of: Journal of biochemistry. Volume 167:Number 6(2020)
• Page Start: 549
• Page End: 555
• Publication Date: 2020-04-13
• Subjects: absorption spectroscopy -- ferredoxin -- protein–protein interaction -- redox-dependent structural change -- X-ray crystallography; Biochemistry -- Periodicals; Biochemistry -- Periodicals; Electronic journals; 572.05
• DOI: 10.1093/jb/mvaa045
• Languages: English
• ISSNs: 0021-924X

Abstract

Abstract: Plant-type ferredoxin (Fd) is an electron transfer protein in chloroplast. Redox-dependent structural change of Fd controls its association with and dissociation from Fd-dependent enzymes. Among many X-ray structures of oxidized Fd have been reported so far, very likely a given number of them was partially reduced by strong X-ray. To understand the precise structural change between reduced and oxidized Fd, it is important to know whether the crystals of oxidized Fd may or may not be reduced during the X-ray experiment. We prepared the thin plate-shaped Fd crystals from Chlamydomonas reinhardtii and monitored its absorption spectra during experiment. Absorption spectra of oxidized Fd crystals were clearly changed to that of reduced form in an X-ray dose-dependent manner. In another independent experiment, the X-ray diffraction images obtained from different parts of one single crystal were sorted and merged to form two datasets with low and high X-ray doses. An Fo–Fo map calculated from the two datasets showed that X-ray reduction causes a small displacement of the iron atoms in the [2Fe-2S] cluster. Both our spectroscopic and crystallographic studies confirm X-ray dose-dependent reduction of Fd, and suggest a structural basis for its initial reduction step especially in the core of the cluster.