A single bifunctional UDP-GlcNAc/Glc 4-epimerase supports the synthesis of three cell surface glycoconjugates in campylobacter jejuni

Download
  1. Get@NRC: A single bifunctional UDP-GlcNAc/Glc 4-epimerase supports the synthesis of three cell surface glycoconjugates in campylobacter jejuni (Opens in a new window)
AuthorSearch for: ; Search for: ; Search for: ; Search for: ; Search for: ; Search for: ; Search for: ; Search for: ; Search for:
TypeArticle
Journal titleJournal Of Biological Chemistry
Volume280
Issue6
Pages47924802; # of pages: 11
Subjectangle; assay; Bacteria; bacterial; binding; BINDING-SITE; Campylobacter; Campylobacter jejuni; Canada; capsule; carbohydrate; Carbohydrates; cell; CELL-SURFACE; DIFFERENCE; ENZYME; EQUILIBRIUM; Glycoconjugates; glycoprotein; Glycosyltransferases; HIGH-RESOLUTION; kinetic; lipooligosaccharide; magic angle; magic angle spinning; MUTANT; N-linked; NMR; PARAMETERS; protein; Pseudomonas; Pseudomonas aeruginosa; PSEUDOMONAS-AERUGINOSA; RESIDUES; RESOLUTION; SITE; structure; sugar; SUGARS; surface; Synthesis
AbstractThe major cell-surface carbohydrates (lipooligosaccharide, capsule and glycoprotein N-linked heptasaccharide) of Campylobacter jejuni NCTC 11168 contain Gal and/or GalNAc residues. GalE is the sole annotated UDP-glucose 4-epimerase in this bacterium. The presence of GalNAc residues in these carbohydrates suggested that GalE may be an UDP-GlcNAc 4-epimerase. GalE was shown to epimerize UDP-Glc and UDP-GlcNAc in coupled assays with C. jejuni glycosyltransferases and in sugar nucleotide epimerization equilibria studies. Thus, GalE possesses UDP-GlcNAc 4-epimerase activity and was renamed Gne. The Km(app) of a purified MalE-Gne fusion protein for UDP-GlcNAc and UDP-GalNAc are 1087M and 1070 M while those for UDP-Glc and UDP-Gal are 780 M and 784 M. The kcat and kcat/ Km(app) were three to four times higher for UDP-GalNAc and UDP-Gal than for UDP-GlcNAc and UDP-Glc. The comparison of the kinetic parameters of MalE-Gne to those of other characterized bacterial UDP-GlcNAc 4-epimerases indicated that Gne is a bifunctional UDP-GlcNAc/Glc 4-epimerase. The UDP-sugar binding site of Gne was modeled using the structure of the UDP-GlcNAc 4-epimerase WbpP from Pseudomonas aeruginosa. Small differences were noted and these may explain the bifunctional character of the C. jejuni Gne. In a gne mutant of C. jejuni, the LOS was shown by CE-MS to be truncated by at least five sugars. Furthermore, both the glycoprotein N-linked heptasaccharide and capsule were no longer detectable by high resolution magic angle spinning NMR. These data indicate that Gne is the enzyme providing Gal and GalNAc residues for the synthesis of all three cell-surface carbohydrates in C. jejuni NCTC 11168
Publication date
LanguageEnglish
AffiliationNational Research Council Canada; NRC Institute for Biological Sciences
Peer reviewedNo
NRC numberBERNATCHEZ2005
NPARC number9387849
Export citationExport as RIS
Report a correctionReport a correction
Record identifierae8a0e04-9758-498a-aa40-a5297614db13
Record created2009-07-10
Record modified2016-05-09
Bookmark and share
  • Share this page with Facebook (Opens in a new window)
  • Share this page with Twitter (Opens in a new window)
  • Share this page with Google+ (Opens in a new window)
  • Share this page with Delicious (Opens in a new window)