title: The Hexapeptide inhibitor of Galbeta 1,3GalNAc-specific alpha 2,3-sialyltransferase as a generic inhibitor of sialyltransferases.
abstract: The mammalian Galbeta1,3GalNAc-specific alpha2,3-sialyltransferase (ST3Gal I) was expressed as a secreted glycoprotein in High Five (Trichoplusia ni) cells. Using this recombinant ST3Gal I, we screened the synthetic hexapeptide combinatorial library to explore a sialyltransferase inhibitor. We found that the hexapeptide, NH(2)-GNWWWW, exhibited the most strong inhibition of ST3Gal I among five different hexapeptides that were finally selected. The kinetic analysis of ST3Gal I inhibition demonstrated that this hexapeptide could act as a competitive inhibitor (K(i) = 1.1 microm) on CMP-NeuAc binding to the enzyme. Moreover, the hexapeptide was shown to strongly inhibit both N-glycan-specific alpha2,3- and alpha2,6-sialyltranferase in vitro, suggesting that this peptide may inhibit the broad range of sialyltransferases regardless of their linkage specificity. The inhibitory activity in vivo was investigated by RCA-I lectin blot analyses and by metabolic d-[6-(3)H]GlcNH(2) radiolabeling analyses of N- and O-linked oligosaccharides in Chines hamster ovary cells. Our results demonstrate that the hexapeptide can act as a generic inhibitor of the N- and O-glycan-specific sialyltransferases in mammalian cells, which results in the significantly reduced NeuAc expression on cellular glycoproteins in vivo.
authors.affiliation: Animal Cell and Medical Glycobiology Laboratory and Liver Cell Signal Transduction Laboratory, Korea Research Institute of Bioscience and Biotechnology, P.O. Box 115, Yusung, Taejon 305-333, South Korea.
authors.forename: Ki-Young
authors.initials: KY
authors.lastname: Lee
authors.forename: Hyung Gu
authors.initials: HG
authors.lastname: Kim
authors.forename: Mi Ran
authors.initials: MR
authors.lastname: Hwang
authors.forename: Jung Il
authors.initials: JI
authors.lastname: Chae
authors.forename: Jai Myung
authors.initials: JM
authors.lastname: Yang
authors.forename: Young Choon
authors.initials: YC
authors.lastname: Lee
authors.forename: Young Kug
authors.initials: YK
authors.lastname: Choo
authors.forename: Young Ik
authors.initials: YI
authors.lastname: Lee
authors.forename: Sang-Soo
authors.initials: SS
authors.lastname: Lee
authors.forename: Su-Il
authors.initials: SI
authors.lastname: Do
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001667:Binding, Competitive; D016466:CHO Cells; D002460:Cell Line; D006224:Cricetinae; D018076:DNA, Complementary / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004591:Electrophoresis, Polyacrylamide Gel; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D007313:Insecta; D007700:Kinetics; D008969:Molecular Sequence Data; D009036:Moths; D019151:Peptide Library; D010455:Peptides / Q000737:chemistry; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000378:metabolism; D012799:Sialyltransferases / Q000037:antagonists & inhibitors*; D014415:Tunicamycin / Q000494:pharmacology; D000094663:beta-Galactoside alpha-2,3-Sialyltransferase
chemical_list: D018076:DNA, Complementary; D004791:Enzyme Inhibitors; D019151:Peptide Library; D010455:Peptides; D011994:Recombinant Proteins; D014415:Tunicamycin; D012799:Sialyltransferases; D000094663:beta-Galactoside alpha-2,3-Sialyltransferase