1HXJ

CRYSTAL STRUCTURE OF THE MAIZE ZM-P60.1 BETA-GLUCOSIDASE


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.05 Å
  • R-Value Free: 0.229 
  • R-Value Work: 0.168 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Insights into the functional architecture of the catalytic center of a maize beta-glucosidase Zm-p60.1

Zouhar, J.Vevodova, J.Marek, J.Damborsky, J.Su, X.-D.Brzobohaty, B.

(2001) Plant Physiol. 127: 973-985


  • PubMed Abstract: 
  • The maize (Zea mays) beta-glucosidase Zm-p60.1 has been implicated in regulation of plant development by the targeted release of free cytokinins from cytokinin-O-glucosides, their inactive storage forms. The crystal structure of the wild-type enzyme ...

    The maize (Zea mays) beta-glucosidase Zm-p60.1 has been implicated in regulation of plant development by the targeted release of free cytokinins from cytokinin-O-glucosides, their inactive storage forms. The crystal structure of the wild-type enzyme was solved at 2.05-A resolution, allowing molecular docking analysis to be conducted. This indicated that the enzyme specificity toward substrates with aryl aglycones is determined by aglycone aromatic system stacking with W373, and interactions with edges of F193, F200, and F461 located opposite W373 in a slot-like aglycone-binding site. These aglycone-active site interactions recently were hypothesized to determine substrate specificity in inactive enzyme substrate complexes of ZM-Glu1, an allozyme of Zm-p60.1. Here, we test this hypothesis by kinetic analysis of F193I/Y/W mutants. The decreased K(m) of all mutants confirmed the involvement of F193 in determining enzyme affinity toward substrates with an aromatic aglycone. It was unexpected that a 30-fold decrease in k(cat) was found in F193I mutant compared with the wild type. Kinetic analysis and computer modeling demonstrated that the F193-aglycone-W373 interaction not only contributes to aglycone recognition as hypothesized previously but also codetermines catalytic rate by fixing the glucosidic bond in an orientation favorable for attack by the catalytic pair, E186 and E401. The catalytic pair, assigned initially by their location in the structure, was confirmed by kinetic analysis of E186D/Q and E401D/Q mutants. It was unexpected that the E401D as well as C205S and C211S mutations dramatically impaired the assembly of a catalysis-competent homodimer, suggesting novel links between the active site structure and dimer formation.


    Related Citations: 
    • Purification, Crystallization and Preliminary X-Ray Analysis of a Maize Cytokinin-Glucoside-Specific Beta-Glucosidase
      Vevodova, J.,Marek, J.,Zouhar, J.,Brzobohaty, B.,Su, X.-D.
      (2001) Acta Crystallogr.,Sect.D 57: 140


    Organizational Affiliation

    Department of Functional Genomics and Proteomics, Faculty of Science, Masaryk University, Kotláská 2, CZ-61137 Brno, Czech Republic.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
BETA-GLUCOSIDASE
A, B
507Zea maysGene Names: GLU1
EC: 3.2.1.182, 3.2.1.21
Find proteins for P49235 (Zea mays)
Go to UniProtKB:  P49235
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.05 Å
  • R-Value Free: 0.229 
  • R-Value Work: 0.168 
  • Space Group: P 1 21 1
Unit Cell:
Length (Å)Angle (°)
a = 55.664α = 90.00
b = 110.718β = 92.10
c = 72.940γ = 90.00
Software Package:
Software NamePurpose
SCALEPACKdata scaling
AMoREphasing
DENZOdata reduction
CNSrefinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2003-01-21
    Type: Initial release
  • Version 1.1: 2008-04-27
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance