tailieunhanh - Báo cáo khoa học: Crystal structure of highly thermostable glycerol kinase from a hyperthermophilic archaeon in a dimeric form

The crystal structure of glycerol kinase from the hyperthermophilic archa-eon Thermococcus kodakaraensis(Tk-GK) in a dimeric form was deter-mined at a resolution of A˚ . This is the first crystal structure of a hyperthermophilic glycerol kinase. | ễFEBS Journal Crystal structure of highly thermostable glycerol kinase from a hyperthermophilic archaeon in a dimeric form Yuichi Koga1 Ryota Katsumi1 Dong-Ju You1 Hiroyoshi Matsumura2 3 Kazufumi Takano1 3 and Shigenori Kanaya1 1 Department of Materialand Life Science Graduate Schoolof Engineering Osaka University Japan 2 Department of Applied Chemistry Graduate Schoolof Engineering Osaka University Japan 3 CRESTO JST Osaka Japan Keywords crystal structure glycerol kinase ion pair thermalstability Thermococcus kodakaraensis Correspondence S. Kanaya Department of Materialand Life Science Graduate School of Engineering Osaka University 2-1 Yamadaoka Suita Osaka 565-0871 Japan Fax 81 6 6879 7938 Tel 81 6 6879 7938 E-mail kanaya@ These authors contributed equally to this work Received 3 January 2008 revised 25 February 2008 accepted 17 March 2008 doi The crystal structure of glycerol kinase from the hyperthermophilic archaeon Thermococcus kodakaraensis Tk-GK in a dimeric form was determined at a resolution of A. This is the first crystal structure of a hyperthermophilic glycerol kinase. The overall structure of the Tk-GK dimer is very similar to that of the Escherichia coli glycerol kinase Ec-GK dimer. However two dimers of Ec-GK can associate into a tetramer with a twofold axis whereas those of Tk-GK cannot. This may be the reason why Tk-GK is not inhibited by fructose 1 6-bisphosphate because the fructose 1 6-bisphosphate binding site is produced only when a tetrameric structure is formed. Differential scanning calorimetry analyses indicate that Tk-GK is a highly thermostable protein with a melting temperature Tm of C for the major transition. This value is higher than that of Ec-GK by C. Comparison of the crystal structures of Tk-GK and Ec-GK indicate that there is a marked difference in the number of ion pairs in the a16 helix. Four ion pairs termed IP1-IP4 are formed in this helix in the Tk-GK .