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Crystallization of the ribosome inactivating protein ML1 from Viscum album (mistletoe) complexed with
E C Sweeney1, R A Palmer, U Pfüller
1Department of Crystallography, Birkbeck College, University of London, U.K.
Abstract:
A ribosome inactivating protein (ML1) from the mistletoe plant (Viscum album) has been crystallized. The crystals, grown in the presence of beta-D-galactose, are hexagonal, space group P6(1)22 or P6(5)22, a = b = 111.0 A, c = 309.3 A with 24 molecules per unit cell (assuming 33% solvent by weight). The protein of molecular mass 63 kDa is a heterodimer consisting of two chains, A and B, joined by a disulfide bond. The A-chain, 29 kDa, inhibits protein synthesis by depurinating an adenine residue (A4324) in a highly conserved RNA loop of the 28 S ribosomal subunit. The toxicity of the protein is mediated by the B-chain, 34 kDa, which has lectin activity, interacting with sugar residues of glycoproteins and glycolipids on the surface of target cells.