Tuesday, February 7, 2012
The authors of this study published last year in Mol. Bio. Evol. analyzed the evolutionary constraints on the N-glycosylation metabolic pathway across humans, gorillas, chimps, orangutans, and macaques. Glycosylation attaches a glycan, or a chain of sugars known to mediate biological functions in the cell, to a protein. Multiple alignments were obtained of the CDS of each of 52 orthologous genes involved in the N-glycan biosynthesis pathway. The structure of the pathway was derived and represented graphically in order to compare the selection acting on genes with respect to their connectivity, their position in the nearly-linear network, and the rates of evolution of their neighboring genes. The genes involved in glycan synthesis were found to be highly conserved with no evidence of positive selection since the divergence of primates. Additionally, the gene products that were highly interactive with others were found to be more highly constrained and to evolve more slowly, suggesting that connectivity within networks influences evolutionary constraints.