Purification crystallization and preliminary crystallographic analysis of a thermostable endonuclease IV from Thermotoga maritima

摘要

The DNA-repair enzyme endonuclease IV from the thermophilic bacterium Thermotoga maritima MSB8 (reference sequence ) has been expressed in Escherichia coli and crystallized for X-ray analysis. T. maritima endonuclease IV is a 287-amino-acid protein with 32% sequence identity to E. coli endonuclease IV. The protein was purified to homogeneity and was crystallized using the sitting-drop vapor-diffusion method. The protein crystallized in space group P61, with one biological molecule in the asymmetric unit, corresponding to a Matthews coefficient of 2.39 ų Da⁻¹ and 47% solvent content. The unit-cell parameters of the crystals were a = b = 123.2, c = 35.6 Å. Microseeding and further optimization yielded crystals with an X-ray diffraction limit of 2.36 Å. A single 70° data set was collected and processed, resulting in an overall R merge and a completeness of 9.5% and 99.3%, respectively.