Premium
Crystal structure of highly thermostable glycerol kinase from a hyperthermophilic archaeon in a dimeric form
Author(s) -
Koga Yuichi,
Katsumi Ryota,
You DongJu,
Matsumura Hiroyoshi,
Takano Kazufumi,
Kanaya Shigenori
Publication year - 2008
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/j.1742-4658.2008.06410.x
Subject(s) - glycerol kinase , chemistry , dimer , crystallography , crystal structure , tetramer , helix (gastropod) , glycerol , stereochemistry , enzyme , biochemistry , biology , ecology , organic chemistry , snail
The crystal structure of glycerol kinase from the hyperthermophilic archaeon Thermococcus kodakaraensis (Tk‐GK) in a dimeric form was determined at a resolution of 2.4 Å. 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 ( T m ) of 105.4 °C for the major transition. This value is higher than that of Ec‐GK by 34.1 °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 α16 helix. Four ion pairs, termed IP1–IP4, are formed in this helix in the Tk‐GK structure. To examine whether these ion pairs contribute to the stabilization of Tk‐GK, four Tk‐GK and four Ec‐GK derivatives with reciprocal mutations at the IP1–IP4 sites were constructed. The determination of their stabilities indicates that the removal of each ion pair does not affect the stability of Tk‐GK significantly, whereas the mutations designed to introduce one of these ion pairs stabilize or destabilize Ec‐GK considerably. These results suggest that the ion pairs in the α16 helix contribute to the stabilization of Tk‐GK in a cooperative manner.