Structural analysis of the asparagine-linked glycans from the procyclic Trypanosoma brucei and its glycosylation mutants resistant to Concanavalin A killing.
The variant surface glycoprotein of the bloodstream form of Trypanosoma brucei is known to be glycosylated with a range of structures including high mannose and complex types. In contrast, glycosylation in the procyclic form of the parasite appears to be restricted to a single Man(5)GlcNAc(2) structure, as found on its procyclin. To gain a better insight into the developmentally regulated glycosylation pattern, we have structurally defined the full range of N-linked glycans made by the procyclic trypanosomes, as well as two previously described glycosylation mutants generated under Con A selection. It was found that the wild type procyclic cells could synthesize a full range of high mannose type structures from Man(5)GlcNAc(2) to Man(9)GlcNAc(2), with Man(5)GlcNAc(2) as the major component. In contrast, the two mutants mainly synthesized a truncated Man(4)GlcNAc(2) structure, Man alpha 1-3Man alpha 1-6(Man alpha1-3)Man be ta 1-4 GlcNAc beta 1-4GlcNAc, a significant portion of which was further extended by a single GlcNAc to form GlcNAc-Man(4)GlcNAc(2) and a single N-acetyllactosamine unit at the 3-arm position to form Gal beta 1-4GlcNAc beta 1-2Man alpha 1-3(Man al pha 1- 3Man alpha 1-6)Man beta 1-4G lcNAc beta 1-4GlcNAc. The results suggest that the procyclic trypanosomes could be induced by Con A selection to synthesize limited hybrid type structures, but in general do not further process their N-linked glycans into multiantennary complex types as the blood stream forms do.
Hwa
K Y
KY
Institute of Biological Chemistry, Academia Sinica, 128 Yen Chiu Yuan Road, Section 2, Nankang, Taipei, 115, Taiwan, ROC. kyhwa@gate.sinica.edu.tw
Khoo
K H
KH
D000818:Animals; D001216:Asparagine; D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D003208:Concanavalin A / Q000494:pharmacology*; D006020:Glycopeptides / Q000737:chemistry*; D006031:Glycosylation; D008358:Mannose / Q000032:analysis; D008969:Molecular Sequence Data; D009154:Mutation; D009844:Oligosaccharides / Q000096:biosynthesis / Q000737:chemistry*; D011134:Polysaccharides / Q000096:biosynthesis* / Q000737:chemistry*; D016339:Spectrometry, Mass, Fast Atom Bombardment; D014346:Trypanosoma brucei brucei / Q000187:drug effects / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*
D006020:Glycopeptides; D009844:Oligosaccharides; D011134:Polysaccharides; D003208:Concanavalin A; D001216:Asparagine; C058642:mannosyl(5)-N-acetyl(2)-glucose; D008358:Mannose