Studies on the Zn-containing S14 ribosomal protein from Thermus thermophilus

The S14 ribosomal protein from the thermophilic organism Thermus thermophilus, which contains a zinc-finger-like motif, namely -C-X2-C-X12-C-X2-C- [Tsiboli, P. & Choli, T. (1995) Biol. Chem. Hoppe-Seyler 376, 127−130], has been overproduced, purified and investigated for its zinc content. According to atomic absorption experiments, the protein contains zinc at a molar ratio of one. Denaturation experiments with simultaneous use of denaturing and chelating agents (guanidine hydrochloride and EDTA), as well as renaturation experiments, have shown both that Zn is strongly bound to the protein and with 1 : 1 Zn/protein stoicheiometry. These findings provide very strong evidence in support of the participation of the zinc-finger motif and the Zn in the formation of a zinc-finger domain.