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Rational Design of a Mononuclear Metal Site into the Archaeal Rieske-type Protein Scaffold

2005; Elsevier BV; Volume: 280; Issue: 10 Linguagem: Inglês

10.1074/jbc.m414051200

1083-351X

Toshio Iwasaki, Asako Kounosu, Ye Tao, Zhongrui Li, Jacob E. Shokes, Nathaniel J. Cosper, Takeo Imai, Akio Urushiyama, Robert A. Scott,

CO2 Reduction Techniques and Catalysts

Proteins containing Rieske-type [2Fe-2S] clusters play essential functions in all three domains of life. We engineered the two histidine ligands to the Rieske-type [2Fe-2S] cluster in the hyperthermophilic archaeal Rieske-type ferredoxin from Sulfolobus solfataricus to modify types and spacing of ligands and successfully converted the metal and cluster type at the redox-active site with a minimal structural change to a native Rieske-type protein scaffold. Spectroscopic analyses unambiguously established a rubredoxin-type mononuclear Fe3+/2+ center at the engineered local metal-binding site (Zn2+ occupies the iron site depending on the expression conditions). These results show the importance of types and spacing of ligands in the in vivo cluster recognition/insertion/assembly in biological metallosulfur protein scaffolds. We suggest that early ligand substitution and displacement events at the local metal-binding site(s) might have primarily allowed the metal and cluster type conversion in ancestral redox protein modules, which greatly enhanced their capabilities of conducting a wide range of unique redox chemistry in biological electron transfer conduits, using a limited number of basic protein scaffolds.