Purification, crystallization and preliminary X-ray diffraction study on pyrimidine nucleoside phosphorylase TTHA1771 from Thermus thermophilus HB8.

Pyrimidine nucleoside phosphorylase (PYNP) catalyzes the reversible phosphorolysis of pyrimidines in the nucleotide-synthesis salvage pathway. In order to study the structure-thermostability relationship of this enzyme, PYNP from the extreme thermophile Thermus thermophilus HB8 (TTHA1771) has been cloned, overexpressed and purified. The TTHA1771 protein was crystallized at 291 K using the oil-microbatch method with PEG 4000 as a precipitant. A native data set was collected to 1.8 A resolution using synchrotron radiation. The crystal belongs to the monoclinic space group P2(1), with unit-cell parameters a = 58.83, b = 76.23, c = 103.86 A, beta = 91.3 degrees.