Partial Structure of Glutamic Acid and Alanine-rich Protein, a Major Surface Glycoprotein of the Insect Stages of Trypanosoma congolense

• Published in: The Journal of biological chemistry 2002-12, Vol.277 (50), p.48899-48904
• Main Authors: Thomson, Lynn M, Lamont, Douglas J, Mehlert, Angela, Barry, J David, Ferguson, Michael A J
• Format: Article
• Language: English
• Subjects: Amino Acid Sequence; Animals; Electrophoresis, Polyacrylamide Gel; Glycosylation; Microscopy, Immunoelectron - methods; Molecular Sequence Data; Protein Conformation; Protozoan Proteins - chemistry; Protozoan Proteins - ultrastructure; Sequence Homology, Amino Acid; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Trypanosoma congolense - chemistry; Trypanosoma congolense - ultrastructure
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M208942200

The tsetse fly transmitted salivarian trypanosome, Trypanosoma congolense of the subgenus Nanomonas , is the most significant of the trypanosomes with respect to the pathology of livestock in sub-Saharan Africa. Unlike the related trypanosome Trypanosoma brucei of the subgenus Trypanozoon , the major surface molecules of the insect stages of T. congolense are poorly characterized. Here, we describe the purification and structural characterization of the glutamic acid and alanine-rich protein, one of the major surface glycoproteins of T. congolense procyclic and epimastigote forms. The glycoprotein is a glycosylphosphatidylinositol-anchored molecule with a galactosylated glycosylphosphatidylinositol anchor containing an sn -1-stearoyl-2- l -3-HPO 4 -1-(2- O -acyl)- d - myo -inositol phospholipid moiety. The 21.6-kDa polypeptide component carries two large mannose- and galactose-containing oligosaccharides linked to threonine residues via phosphodiester linkages. Mass spectrometric analyses of tryptic digests suggest that several or all of the closely related glutamic acid and alanine-rich protein genes are expressed simultaneously in a T. congolense population growing in vitro .