2VXL

Screening a Limited Structure-based Library Identifies UDP-GalNAc- Specific Mutants of alpha-1,3 Galactosyltransferase


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.70 Å
  • R-Value Free: 0.260 
  • R-Value Work: 0.192 

wwPDB Validation   3D Report Full Report


This is version 1.2 of the entry. See complete history


Literature

Screening a Limited Structure-Based Library Identifies Udp-Galnac-Specific Mutants of {Alpha}-1,3-Galactosyltransferase.

Tumbale, P.Jamaluddin, H.Thiyagarajan, N.Acharya, K.R.Brew, K.

(2008) Glycobiology 18: 1036

  • DOI: 10.1093/glycob/cwn083
  • Primary Citation of Related Structures:  
    2VXL, 2VXM

  • PubMed Abstract: 
  • Complex glycans have important roles in biological recognition processes and considerable pharmaceutical potential. The synthesis of novel glycans can be facilitated by engineering glycosyltransferases to modify their substrate specificities. The cho ...

    Complex glycans have important roles in biological recognition processes and considerable pharmaceutical potential. The synthesis of novel glycans can be facilitated by engineering glycosyltransferases to modify their substrate specificities. The choice of sites to modify requires the knowledge of the structures of enzyme-substrate complexes while the complexity of protein structures necessitates the exploration of a large array of multisite mutations. The retaining glycosyltransferase, alpha-1,3-galactosyltransferase (alpha3GT), which catalyzes the synthesis of the alpha-Gal epitope, has strict specificity for UDP-galactose as a donor substrate. Based on the structure of a complex of UDP-galactose with alpha3GT, the specificity for the galactose moiety can be partly attributed to residues that interact with the galactose 2-OH group, particularly His280 and Ala282. With the goal of engineering a variant of bovine alpha3GT with GalNAc transferase activity, we constructed a limited library of 456 alpha3GT mutants containing 19 alternative amino acids at position 280, two each at 281 and 282 and six at position 283. Clones (1500) were screened by assaying partially purified bacterially expressed variants for GalNAc transferase activity. Mutants with the highest levels of GalNAc transferase activity, AGGL or GGGL, had substitutions at all four sites. The AGGL mutant had slightly superior GalNAc transferase activity amounting to about 3% of the activity of the wild-type enzyme with UDP-Gal. This mutant had a low activity with UDP-Gal; its crystallographic structure suggests that the smaller side chains at residues 280-282 form a pocket to accommodate the larger acetamido group of GalNAc. Mutational studies indicate that Leu283 is important for stability in this mutant.


    Organizational Affiliation

    Department of Biomedical Science, College of Biomedical Science, Florida Atlantic University, Glades Road, Boca Raton, FL 33431, USA.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
N-ACETYLLACTOSAMINIDE ALPHA-1,3-GALACTOSYLTRANSFERASEA277Bos taurusMutation(s): 4 
Gene Names: GGTA1
EC: 2.4.1.87
Find proteins for P14769 (Bos taurus)
Explore P14769 
Go to UniProtKB:  P14769
Protein Feature View
Expand
  • Reference Sequence
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
UDP
Query on UDP

Download CCD File 
A
URIDINE-5'-DIPHOSPHATE
C9 H14 N2 O12 P2
XCCTYIAWTASOJW-XVFCMESISA-N
 Ligand Interaction
MN
Query on MN

Download CCD File 
A
MANGANESE (II) ION
Mn
WAEMQWOKJMHJLA-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.70 Å
  • R-Value Free: 0.260 
  • R-Value Work: 0.192 
  • Space Group: P 31 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 70.197α = 90
b = 70.197β = 90
c = 126.991γ = 120
Software Package:
Software NamePurpose
REFMACrefinement
MOSFLMdata reduction
SCALAdata scaling
MOLREPphasing

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2008-09-23
    Type: Initial release
  • Version 1.1: 2011-05-07
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance