Titre
Protein C-mannosylation is enzyme-catalysed and uses dolichyl-phosphate-mannose as a precursor.
Type
article
Institution
Externe
Périodique
Auteur(s)
Doucey, M.A.
Auteure/Auteur
Hess, D.
Auteure/Auteur
Cacan, R.
Auteure/Auteur
Hofsteenge, J.
Auteure/Auteur
Liens vers les personnes
ISSN
1059-1524
Statut éditorial
Publié
Date de publication
1998
Volume
9
Numéro
2
Première page
291
Dernière page/numéro d’article
300
Langue
anglais
Résumé
C-mannosylation of Trp-7 in human ribonuclease 2 (RNase 2) is a novel kind of protein glycosylation that differs fundamentally from N- and O-glycosylation in the protein-sugar linkage. Previously, we established that the specificity determinant of the acceptor substrate (RNase 2) consists of the sequence -x-x-W, where the first Trp becomes C-mannosylated. Here we investigated the reaction with respect to the mannosyl donor and the involvement of a glycosyltransferase. C-mannosylation of Trp-7 was reduced 10-fold in CHO (Chinese hamster ovary) Lec15 cells, which are deficient in dolichyl-phosphate-mannose (Dol-P-Man) synthase activity, compared with wild-type cells. This was not a result of a decrease in C-mannosyltransferase activity. Rat liver microsomes were used to C-mannosylate the N-terminal dodecapeptide from RNase 2 in vitro, with Dol-P-Man as the donor. This microsomal transferase activity was destroyed by heat and protease treatment, and displayed the same acceptor substrate specificity as the in vivo reaction studied previously. The C-C linkage between the indole and the mannosyl moiety was demonstrated by tandem electrospray mass spectrometry analysis of the product. GDP-Man, in the presence of Dol-P, functioned as a precursor in vitro with membranes from wild-type but not CHO Lec15 cells. In contrast, with Dol-P-Man both membrane preparations were equally active. It is concluded that a microsomal transferase catalyses C-mannosylation of Trp-7, and that the minimal biosynthetic pathway can be defined as: Man -> -> GDP-Man -> Dol-P-Man -> (C2-Man-)Trp.
Sujets
PID Serval
serval:BIB_17F018151834
PMID
Date de création
2008-01-28T07:28:08.946Z
Date de création dans IRIS
2025-05-20T17:41:14Z