Skip Navigation


Glycobiology Advance Access originally published online on December 22, 2004
Glycobiology 2005 15(5):489-500; doi:10.1093/glycob/cwi034
This Article
Right arrow Full Text Freely available
Right arrow FREE Full Text (PDF) Freely available
Right arrow All Versions of this Article:
15/5/489    most recent
cwi034v1
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in ISI Web of Science
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Add to My Personal Archive
Right arrow Download to citation manager
Right arrow Search for citing articles in:
ISI Web of Science (1)
Right arrowRequest Permissions
Right arrow Disclaimer
Google Scholar
Right arrow Articles by Ercan, A.
Right arrow Articles by West, C. M.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Ercan, A.
Right arrow Articles by West, C. M.
Social Bookmarking
Add to CiteULike   Add to Connotea   Add to Del.icio.us  
What's this?

Glycobiology vol. 15 no. 5 © Oxford University Press 2004; all rights reserved.

Kinetic analysis of a Golgi UDP-GlcNAc:polypeptide-Thr/Ser N-acetyl-{alpha}-glucosaminyltransferase from Dictyostelium

Altan Ercan and Christopher M. West1

Department of Biochemistry and Molecular Biology, Oklahoma Center for Medical Glycobiology, University of Oklahoma Health Sciences Center, 940 Stanton L. Young Blvd., BMSB 937, Oklahoma City, OK 73104

1To whom correspondence should be addressed; e-mail: cwest2{at}ouhsc.edu

Received on August 29, 2004; revised on November 27, 2004; accepted on November 29, 2004

Mucin-type O-glycosylation in Dictyostelium is initiated in the Golgi by a UDP-GlcNAc:polypeptide-Thr/Ser N-acetyl-{alpha}-glucosaminyltransferase (Dd-pp {alpha}GlcNAcT2) whose sequence is distantly related to the sequences of animal polypeptide-Thr/Ser N-acetyl-{alpha}-galactosaminyltransferases, such as murine Mm-pp {alpha}GalNAcT1. To evaluate the significance of this similarity, highly purified Dd-pp {alpha}GlcNAcT2 was assayed using synthetic peptides derived from known substrates. Dd-pp {alpha}GlcNAcT2 strongly prefers UDP-GlcNAc over UDP-GalNAc, preferentially modifies the central region of the peptide, and modifies Ser in addition to Thr residues. Initial velocity measurements performed over a matrix of UDP-GlcNAc donor and peptide acceptor concentrations indicate that the substrates bind to the enzyme in ordered fashion before the chemical conversion. Substrate inhibition exerted by a second peptide, and the pattern of product inhibition exerted by UDP, suggest that UDP-GlcNAc binds first and the peptide binds second, consistent with data reported for Mm-pp {alpha}GalNAcT1. Two selective competitive inhibitors of Mm-pp {alpha}GalNAcT1, retrieved from a screen of neutral-charge uridine derivatives, also inhibit Dd-pp {alpha}GlcNAcT1 competitively with only slightly less efficacy. Inhibition is specific for Dd-pp {alpha}GlcNAcT2 relative to two other Dictyostelium retaining glycosyltransferases. These data support a phylogenetic model in which the {alpha}GlcNAcT function in unicellular eukaryotes converted to an {alpha}GalNAcT function in the metazoan ortholog while conserving a similar reaction mechanism and active site architecture.

Key words: evolution / inhibitor / mucin type / O-glycosylation / reaction mechanism


Add to CiteULike CiteULike   Add to Connotea Connotea   Add to Del.icio.us Del.icio.us    What's this?


This article has been cited by other articles:


Home page
 GlycobiologyHome page
N. Heise, D. Singh, H. van der Wel, S. O Sassi, J. M Johnson, C. L Feasley, C. M Koeller, J. O Previato, L. Mendonca-Previato, and C. M West
Molecular analysis of a UDP-GlcNAc:polypeptide {alpha}-N-acetylglucosaminyltransferase implicated in the initiation of mucin-type O-glycosylation in Trypanosoma cruzi
Glycobiology, August 1, 2009; 19(8): 918 - 933.
[Abstract] [Full Text] [PDF]


Disclaimer: Please note that abstracts for content published before 1996 were created through digital scanning and may therefore not exactly replicate the text of the original print issues. All efforts have been made to ensure accuracy, but the Publisher will not be held responsible for any remaining inaccuracies. If you require any further clarification, please contact our Customer Services Department.