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Home Journal Highlights New Results Suggest Darwinian Selection Against Asparagine-Linked Glycans in Plasmodium and Toxoplasma
New Results Suggest Darwinian Selection Against Asparagine-Linked Glycans in Plasmodium and Toxoplasma Print E-mail

 

Asparagine-linked glycans (N-glycans) are nearly ubiquitous modifications of secreted and membrane proteins in the ER lumen. Positive Darwinian selection forN-glycan sites takes place in the vast majority of eukaryotes, which use N-glycans for quality control of glycoprotein folding. G. Guy Bushkin and John Samuelson of Boston University Goldman School of Dental Medicine et al. use new lectin probes to settle controversies concerning the composition of Plasmodium and Toxoplasma N-glycans. In addition, they present evidence that negative selection occurs against N-glycans in Plasmodium and Toxoplasma, whose apicoplast proteins pass through the ER prior to threading into the plastid-derived organelle. In particular, they show that PlasmodiumN-glycans are just one or two sugars long rather than the 14 sugars of the host, says Samuelson. "Toxoplasma has an extraordinarily low density of N-glycan sites, so that nearly half of the apicoplast proteins contain no N-glycans. Finally, occupation of N-glycan sites is markedly reduced in apicoplast proteins of both Plasmodium and Toxoplasma."

(G. G. Bushkin, D. M. Ratner, J. Cui, S. Banerjee, M. T. Duraisingh, C. V. Jennings, J. D. Dvorin, M.-J. Gubbels, S. D. Robertson, M. Steffen, B. R. O'Keefe, P. W. Robbins, and J. Samuelson. 2010. Suggestive evidence for Darwinian selection against asparagine-linked glycans of Plasmodium falciparum and Toxoplasma gondii. Eukaryot. Cell 9:228-241.)