Expression, crystallization and preliminary X-ray diffraction analysis of a modification subunit of a putative type I restriction enzyme from Vibrio vulnificus YJ016.

Modification (HsdM) and specificity (HsdS) subunits are constituents of an active methyltransferase (MTase) of multifunctional type I restriction enzymes. To provide a molecular background on HsdM, a putative hsdM gene from Vibrio vulnificus YJ016 (HsdM_Vv) was cloned and the expressed protein was purified and crystallized from 22%(w/v) polyethylene glycol 8000, 0.02 M imidazole pH 7.5 and 5 mM beta-mercaptoethanol. Diffraction data were collected to 1.86 A resolution using synchrotron radiation. The crystal belonged to the tetragonal space group P4(1)2(1)2 or P4(3)2(1)2, with unit-cell parameters a = b = 78.9, c = 165.8 A. With one molecule in the asymmetric unit, the crystal volume per unit protein weight was 2.12 A(3) Da(-1), with a solvent content of 42%.