Crystallization of Newcastle disease virus hemagglutinin-neuraminidase glycoprotein

The hemagglutinin-neuraminidase (HN) glycoprotein of Newcastle disease viru s was isolated by cleaving HN (cHN) from reconstituted virosome with chymot rypsin. N-terminal sequence analysis of the purified cHN showed that chymot rypsin cleavage had occurred at amino acid 123, freeing the C-terminal 454 amino acids. The purified cHN retained its neuraminidase and receptor bindi ng activities and reacted with specific monoclonal antibodies, showing that the isolated cHN was biologically and antigenically functional. The crysta ls of the cHN were obtained in acetate buffer (pH 4.6) containing polyethyl ene glycol 3350 and ammonium sulfate and belong to the orthorhombic space g roup P2(1)2(1)2(1) with unit cell dimension of approximately a = 72 Angstro m, b = 78 Angstrom, and c = 198 Angstrom. Crystals of cHN grown in the pres ence of sialic acid (Neu5Ac) were grown in HEPES buffer (pH 6.2) containing polyethylene glycol 3350 and belong to the hexagonal space groups P6, or P 6(5) with unit cell dimensions of a = b = 137.5 Angstrom and c = 116.6 Angs trom. The orthorhombic crystals produced in this study diffract X rays to a t least 2.0-Angstrom resolution, thereby setting the stage for the solution of the three-dimensional structure of the HN glycoprotein of a paramyxovir us. (C) 2000 Academic Press.