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Identification of the active site of DS-epimerase 1 and requirement of N-glycosylation for enzyme function.

Pacheco, Benny LU ; Maccarana, Marco LU ; Goodlett, David R; Malmström, Anders LU and Malmström, Lars LU (2009) In Journal of Biological Chemistry 284(3). p.1741-1747
Abstract
Dermatan sulfate is a highly sulfated polysaccharide and has a variety of biological functions in development and disease. Iduronic acid domains in dermatan sulfate, which are formed by the action of two DS-epimerases, have a key role in mediating these functions. We have identified the catalytic site and three putative catalytic residues in DS-epimerase 1, His205, Tyr261 and His450, by tertiary structure modeling and amino acid conservation to heparinase II. These residues were systematically mutated to alanine or more conserved residues, which resulted in complete loss of epimerase activity. Based on these data, and the close relationship between lyase and epimerase reactions, we propose a model where His450 functions as a general base... (More)
Dermatan sulfate is a highly sulfated polysaccharide and has a variety of biological functions in development and disease. Iduronic acid domains in dermatan sulfate, which are formed by the action of two DS-epimerases, have a key role in mediating these functions. We have identified the catalytic site and three putative catalytic residues in DS-epimerase 1, His205, Tyr261 and His450, by tertiary structure modeling and amino acid conservation to heparinase II. These residues were systematically mutated to alanine or more conserved residues, which resulted in complete loss of epimerase activity. Based on these data, and the close relationship between lyase and epimerase reactions, we propose a model where His450 functions as a general base abstracting the C5-proton from glucuronic acid. Subsequent cleavage of the glycosidic linkage by Tyr261 generates a 4,5-unsaturated hexuronic intermediate, which is protonated at the C5-carbon by His205 from the side of the sugar plane opposite to the side of previous proton abstraction. Concomitant recreation of the glycosidic linkage ends the reaction generating iduronic acid. In addition, we show that proper N-glycosylation of DS-epimerase 1 is required for enzyme activity. This study represents the first description of the structural basis for epimerization by a glycosaminoglycan epimerase. (Less)
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author
organization
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type
Contribution to journal
publication status
published
subject
in
Journal of Biological Chemistry
volume
284
issue
3
pages
1741 - 1747
publisher
ASBMB
external identifiers
  • wos:000262330100044
  • pmid:19004833
  • scopus:59449098994
ISSN
1083-351X
DOI
10.1074/jbc.M805479200
language
English
LU publication?
yes
id
78cec788-641a-46e3-85ee-620e8a3b7293 (old id 1271551)
alternative location
http://www.ncbi.nlm.nih.gov/pubmed/19004833?dopt=Abstract
date added to LUP
2008-12-04 14:55:57
date last changed
2017-08-27 05:47:55
@article{78cec788-641a-46e3-85ee-620e8a3b7293,
  abstract     = {Dermatan sulfate is a highly sulfated polysaccharide and has a variety of biological functions in development and disease. Iduronic acid domains in dermatan sulfate, which are formed by the action of two DS-epimerases, have a key role in mediating these functions. We have identified the catalytic site and three putative catalytic residues in DS-epimerase 1, His205, Tyr261 and His450, by tertiary structure modeling and amino acid conservation to heparinase II. These residues were systematically mutated to alanine or more conserved residues, which resulted in complete loss of epimerase activity. Based on these data, and the close relationship between lyase and epimerase reactions, we propose a model where His450 functions as a general base abstracting the C5-proton from glucuronic acid. Subsequent cleavage of the glycosidic linkage by Tyr261 generates a 4,5-unsaturated hexuronic intermediate, which is protonated at the C5-carbon by His205 from the side of the sugar plane opposite to the side of previous proton abstraction. Concomitant recreation of the glycosidic linkage ends the reaction generating iduronic acid. In addition, we show that proper N-glycosylation of DS-epimerase 1 is required for enzyme activity. This study represents the first description of the structural basis for epimerization by a glycosaminoglycan epimerase.},
  author       = {Pacheco, Benny and Maccarana, Marco and Goodlett, David R and Malmström, Anders and Malmström, Lars},
  issn         = {1083-351X},
  language     = {eng},
  number       = {3},
  pages        = {1741--1747},
  publisher    = {ASBMB},
  series       = {Journal of Biological Chemistry},
  title        = {Identification of the active site of DS-epimerase 1 and requirement of N-glycosylation for enzyme function.},
  url          = {http://dx.doi.org/10.1074/jbc.M805479200},
  volume       = {284},
  year         = {2009},
}