ACYLATION OF THE MARBURG VIRUS GLYCOPROTEIN

The surface protein of Marburg virus (GP) is modified by acylation, as shown by labeling with [H-3]myristic and [H-3]palmitic acid. Acylatio n of GP also occurred when it was expressed in insect cells with the b aculovirus expression system. Gas chromatographic analyses of the boun d fatty acids indicated that exogenously added [H-3]myristic acid was partly metabolized to palmitic and stearic acid. To elucidate the natu re of the fatty acid bond, [H-3]palmitic acid-labeled GP was treated w ith mercaptoethanol. Since the fatty acids were removed by this treatm ent, it is concluded that the linkage is of the thioester type. A puta tive attachment site for thioester-linked fatty acids consisting of tw o cysteine residues located between the transmembrane anchor and the c arboxy-terminal cytoplasmic tail of GP (Cys(671) and Cys(673)) could b e identified. Site-directed mutagenesis of these two amino acids to al anine residues clearly demonstrated that both cysteines could serve as acylation sites. (C) 1995 Academic Press, Inc.