Oligosaccharyltransferase is highly specific for the hydroxy amino acid in Asn‐Xaa‐Thr/Ser

FEBS Letters

Bartoschek, Achim¹  Klein, Roger A¹  Breuer, Wilhelm¹  Bause, Ernst¹  Hardt, Birgit¹ 

[1] Institut für Physiologische Chemie, Nussallee 11, 53115 Bonn, Germany

关键词: Oligosaccharyltransferase;    Stereospecificity;    Threonine analogue;    Hydrophobic binding site;    Enzyme kinetics;    Hnv;    hydroxynorvaline;    Hnl;    hydroxynorleucine;    OST;    oligosaccharyltransferase;   

DOI  :  10.1016/S0014-5793(01)02641-2

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Pig liver oligosaccharyltransferase (OST), which is involved in the en bloc transfer of the Dol-PP-linked GlcNAc₂-Man₉-Glc₃ precursor on to asparagine residues in the Asn-Xaa-Thr/Ser sequence, is highly stereospecific for the conformation of the 3-carbon atom in the hydroxy amino acid. Moreover, substitution of the hydroxy group by either SH as in cysteine, or NH₂ as in β,γ-diamino-butanoic acid as reported previously [Bause, E. et al., Biochem. J. 312 (1995) 979–985], followed by the determination of the pH optimum for enzymatic activity, indicates that neither a negative nor a positive charge in the hydroxy amino acid position is tolerated by the enzyme. Binding of the threonine β-methyl group by OST is also specific, with serine, L-threo-β-hydroxynorvaline and L-β-hydroxynorleucine containing tripeptides all bound much less efficiently than the threonine peptide itself. The data are interpreted in terms of a highly stereospecific hydrophobic binding pocket for the threonine CH₃-CH(OH) group.

【 授权许可】

Unknown