Structure of Yeast Oligosaccharyltransferase Gives Insight into Eukaryotic N-Glycosylation
The Emerging research field of glycobiology deals with biosynthesis, structure and the diverse functions of sugary molecular appendages. One key question is how the diverse set of sugar molecules reach the proteins.
ETH researchers in the groups led by Kaspar Locher of the Institute of Molecular Biology and Biophysics and Markus Aebi of the Institute of Microbiology have now taken a decisive step forwards in this area: they have determined the three-dimensional structure of oligosaccharyltransferase (OST) in yeast. "This is the enzyme that connects proteins to sugar trees," explains Rebekka Wild, one of the three lead authors of the report in Science in which the ETH researchers present their findings. (Science 2018;359:545-550.)
Determining the structure of OST was not easy: to start with, Jilliane Eyring, the third lead author of the report, modified the yeast cells so that the enzyme could be targeted and purified. Wild first had to extract the enzyme, which is embedded in a membrane in the cell, from large quantities of yeast cells and then purify it in a laborious procedure. "Nine litres of yeast produced about 0.2 milligrams of enzyme," she says. The OST molecules were applied to a small grid, flash-frozen as individual, separate particles and imaged using a high-resolution cryo-electron microscope.
Read more at: https://phys.org/news/2018-02-sugar-protein.html#jCp