Structural characteristics of Halophilic proteins investigated by X-ray crystallography

Arai, Shigeki; Yonezawa, Yasushi*; Adachi, Motoyasu; Tamada, Taro; Tokunaga, Hiroko*; Ishibashi, Matsujiro*; Tokunaga, Masao*; Kuroki, Ryota

Halophilic proteins have unique structural characteristics: high content of acidic residues creating negatively charged surface, high reversibility of tertiary structure and activity even in high salt concentration, which make it possible to create potent adhesives for metal ions. As part of our structure-function studies for halophilic proteins, we succeeded in crystallization of several halophilic proteins using divalent metal ions as additives. Here, we show successful examples of structural determination of three halophilic proteins: two are alkaline phosphatase from sp.593 (HaAP) and -Lactamase from sp.560 (HaBLA) determined to 2.1 and 2.0 resolution, respectively, and the other is nucleoside diphosphate kinase from sp.593 (HaNDK) determined to 2.3 resolution.