Open AccessCrystallization and preliminary X‐ray analysis of human MTH1 with a homogeneous N‐terminus
Author(s) -
Koga Yukari,
Inazato Miyuki,
Nakamura Teruya,
Hashikawa Chie,
Chirifu Mami,
Michi Asuka,
Yamashita Taku,
Toma Sachiko,
Kuniyasu Akihiko,
Ikemizu Shinji,
Nakabeppu Yusaku,
Yamagata Yuriko
Publication year - 2013
Publication title -
acta crystallographica section f
Language(s) - English
Resource type - Journals
ISSN - 1744-3091
DOI - 10.1107/s1744309112048002
Subject(s) - crystallization , homogeneous , x ray , crystallography , chemistry , materials science , biophysics , biology , physics , optics , thermodynamics , organic chemistry
Human MTH1 (hMTH1) is an enzyme that hydrolyses several oxidized purine nucleoside triphosphates to their corresponding nucleoside monophosphates. Crystallographic studies have shown that the accurate mode of interaction between 8‐oxoguanine and hMTH1 cannot be understood without determining the positions of the H atoms, as can be observed in neutron and/or ultrahigh‐resolution X‐ray diffraction studies. The hMTH1 protein prepared in the original expression system from Escherichia coli did not appear to be suitable for obtaining high‐quality crystals because the hMTH1 protein had heterogeneous N‐termini of Met1 and Gly2 that resulted from N‐terminal Met excision by methionine aminopeptidase from the E. coli host. To obtain homogeneous hMTH1, the Gly at the second position was replaced by Lys. As a result, mutant hMTH1 protein [hMTH1(G2K)] with a homogeneous N‐terminus could be prepared and high‐quality crystals which diffracted to near 1.1 Å resolution using synchrotron radiation were produced. The new crystals belonged to space group P 2 1 2 1 2 1 , with unit‐cell parameters a = 46.36, b = 47.58, c = 123.89 Å.