1YRO

Crystal structure of beta14,-galactosyltransferase mutant ARG228Lys in complex with alpha-lactalbumin in the presence of UDP-galactose and Mn


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.9 Å
  • R-Value Free: 0.225 
  • R-Value Work: 0.189 

wwPDB Validation 3D Report Full Report


This is version 1.3 of the entry. See complete history

Literature

Mutation of Arginine 228 to Lysine Enhances the Glucosyltransferase Activity of Bovine beta-1,4-Galactosyltransferase I

Ramakrishnan, B.Boeggeman, E.Qasba, P.K.

(2005) Biochemistry 44: 3202-3210

  • DOI: 10.1021/bi0479454

  • PubMed Abstract: 
  • Beta-1,4-galactosyltransferase I (beta4Gal-T1) normally transfers Gal from UDP-Gal to GlcNAc in the presence of Mn(2+) ion (Gal-T activity) and also transfers Glc from UDP-Glc to GlcNAc (Glc-T activity), albeit at only 0.3% efficiency. In addition, a ...

    Beta-1,4-galactosyltransferase I (beta4Gal-T1) normally transfers Gal from UDP-Gal to GlcNAc in the presence of Mn(2+) ion (Gal-T activity) and also transfers Glc from UDP-Glc to GlcNAc (Glc-T activity), albeit at only 0.3% efficiency. In addition, alpha-lactalbumin (LA) enhances this Glc-T activity more than 25 times. Comparison of the crystal structures of UDP-Gal- and UDP-Glc-bound beta4Gal-T1 reveals that the O4 hydroxyl group in both Gal and Glc moieties forms a hydrogen bond with the side chain carboxylate group of Glu317. The orientation of the O4 hydroxyl of glucose causes a steric hindrance to the side chain carboxylate group of Glu317, accounting for the enzyme's low Glc-T activity. In this study, we show that mutation of Arg228, a residue in the vicinity of Glu317, to lysine (R228K-Gal-T1) results in a 15-fold higher Glc-T activity, which is further enhanced by LA to nearly 25% of the Gal-T activity of the wild type. The kinetic parameters indicate that the main effect of the mutation of Arg228 to lysine is on the k(cat) of Glc-T, which increases 3-4-fold, both in the absence and in the presence of LA; simultaneously, the k(cat) for the Gal-T reaction is reduced 30-fold. The crystal structure of R228K-Gal-T1 complexed with LA, UDP-Gal, and Mn(2+) determined at 1.9 A resolution shows that the Asp318 side chain exhibits a minor alternate conformation, compared to that in the wild type. This alternate conformation now causes a steric hindrance to the O4 hydroxyl group of the Gal moiety of UDP-Gal, probably causing the dissociation of UDP-Gal and the reduced k(cat) of the Gal-T reaction.


    Organizational Affiliation

    Structural Glycobiology Section, Laboratory of Experimental and Computational Biology, Center for Cancer Research, National Cancer Institute-Frederick, Frederick, Maryland 21702-1201, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
ALPHA-LACTALBUMIN
A, C
123Mus musculusMutation(s): 0 
Gene Names: Lalba
Find proteins for P29752 (Mus musculus)
Go to UniProtKB:  P29752
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
BETA-1,4-GALACTOSYLTRANSFERASE
B, D
286Bos taurusMutation(s): 2 
Gene Names: B4GALT1 (GALT, GGTB2)
EC: 2.4.1.-
Find proteins for P08037 (Bos taurus)
Go to Gene View: B4GALT1
Go to UniProtKB:  P08037
Small Molecules
Ligands 6 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
MN
Query on MN

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B, D
MANGANESE (II) ION
Mn
WAEMQWOKJMHJLA-UHFFFAOYSA-N
 Ligand Interaction
GDU
Query on GDU

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B, D
GALACTOSE-URIDINE-5'-DIPHOSPHATE
UDP-D-GALACTOPYRANOSE
C15 H24 N2 O17 P2
HSCJRCZFDFQWRP-ABVWGUQPSA-N
 Ligand Interaction
CA
Query on CA

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A, C
CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N
 Ligand Interaction
PG4
Query on PG4

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A, C
TETRAETHYLENE GLYCOL
C8 H18 O5
UWHCKJMYHZGTIT-UHFFFAOYSA-N
 Ligand Interaction
UDP
Query on UDP

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B, D
URIDINE-5'-DIPHOSPHATE
C9 H14 N2 O12 P2
XCCTYIAWTASOJW-XVFCMESISA-N
 Ligand Interaction
MES
Query on MES

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A
2-(N-MORPHOLINO)-ETHANESULFONIC ACID
C6 H13 N O4 S
SXGZJKUKBWWHRA-UHFFFAOYSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.9 Å
  • R-Value Free: 0.225 
  • R-Value Work: 0.189 
  • Space Group: P 1 21 1
Unit Cell:
Length (Å)Angle (°)
a = 57.334α = 90.00
b = 94.087β = 101.64
c = 99.705γ = 90.00
Software Package:
Software NamePurpose
HKL-2000data collection
SCALEPACKdata scaling
CNSrefinement
AMoREphasing
HKL-2000data reduction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2005-03-22
    Type: Initial release
  • Version 1.1: 2007-10-16
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance
  • Version 1.3: 2017-10-11
    Type: Data collection