Forty years of the structure of plant-type ferredoxin

The X-ray structure of a [2Fe-2S]-type ferredoxin (Fd) from Spirulina platensis, solved by a collaborative group led by Profs Masao Kakudo, Yukiteru Katsube and Hiroshi Matsubara, was the first high-resolution structure of a plant-type Fd deposited in the Protein Data Bank. The main chain structure, comprising a [2Fe-2S] cluster ligated by four conserved cysteine residues, together with a molecular evolutionary study based on a series of amino acid sequence determinations, was reported in Nature in 1980. The consequent detailed crystallographic analysis, including crystallization, heavy atom derivatization, data collection, phase calculation and model building, was published by the same group in the Journal of Biochemistry in 1981. The pioneering X-ray analysis of S. platensis Fd at 2.5 Å resolution was a key milestone in structural research on the photosynthetic electron transport chain, informing related and challenging studies on other components of the photosynthetic electron transfer chain.