Differential Labeling of Glycoproteins with Alkynyl Fucose Analogs.
Fucosylated glycans critically regulate the physiological functions of proteins and cells. Alterations in levels of fucosylated glycans are associated with various diseases. For detection and functional modulation of fucosylated glycans, chemical biology approaches using fucose (Fuc) analogs are useful. However, little is known about how efficiently each unnatural Fuc analog is utilized by enzymes in the biosynthetic pathway of fucosylated glycans. We show here that three clickable Fuc analogs with similar but distinct structures labeled cellular glycans with different efficiency and protein specificity. For instance, 6-alkynyl (Alk)-Fuc modified O-Fuc glycans much more efficiently than 7-Alk-Fuc. The level of GDP-6-Alk-Fuc produced in cells was also higher than that of GDP-7-Alk-Fuc. Comprehensive in vitro fucosyltransferase assays revealed that 7-Alk-Fuc is commonly tolerated by most fucosyltransferases. Surprisingly, both protein O-fucosyltransferases (POFUTs) could transfer all Fuc analogs in vitro, likely because POFUT structures have a larger space around their Fuc binding sites. These findings demonstrate that labeling and detection of fucosylated glycans with Fuc analogs depend on multiple cellular steps, including conversion to GDP form, transport into the ER or Golgi, and utilization by each fucosyltransferase, providing insights into design of novel sugar analogs for specific detection of target glycans or inhibition of their functions.
['Ma|Chenyu|C|', 'Takeuchi|Hideyuki|H|0000-0002-2362-5850', 'Hao|Huilin|H|', 'Yonekawa|Chizuko|C|', 'Nakajima|Kazuki|K|', 'Nagae|Masamichi|M|', 'Okajima|Tetsuya|T|0000-0002-3677-648X', 'Haltiwanger|Robert S|RS|0000-0001-7439-9577', 'Kizuka|Yasuhiko|Y|0000-0002-3181-9743']
D001665:Binding Sites D019921:Biotinylation D057930:Click Chemistry D005643:Fucose D005647:Fucosyltransferases D006023:Glycoproteins D006031:Glycosylation D006153:Guanosine Diphosphate D057809:HEK293 Cells D006801:Humans D011134:Polysaccharides D011994:Recombinant Proteins D019700:Thrombospondin 1
fucose glycan fucosyltransferase click chemistry glycan labeling glycosylation notch