3GAR

A PH-DEPENDENT STABLIZATION OF AN ACTIVE SITE LOOP OBSERVED FROM LOW AND HIGH PH CRYSTAL STRUCTURES OF MUTANT MONOMERIC GLYCINAMIDE RIBONUCLEOTIDE TRANSFORMYLASE


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.90 Å
  • R-Value Free: 0.274 
  • R-Value Work: 0.215 
  • R-Value Observed: 0.215 

Starting Model: experimental
View more details

wwPDB Validation   3D Report Full Report


This is version 1.5 of the entry. See complete history


Literature

A pH-dependent stabilization of an active site loop observed from low and high pH crystal structures of mutant monomeric glycinamide ribonucleotide transformylase at 1.8 to 1.9 A.

Su, Y.Yamashita, M.M.Greasley, S.E.Mullen, C.A.Shim, J.H.Jennings, P.A.Benkovic, S.J.Wilson, I.A.

(1998) J Mol Biol 281: 485-499

  • DOI: https://doi.org/10.1006/jmbi.1998.1931
  • Primary Citation of Related Structures:  
    2GAR, 3GAR

  • PubMed Abstract: 

    A mutation in the dimer interface of Escherichia coli glycinamide ribonucleotide transformylase (GarTfase) disrupts the observed pH-dependent association of the wild-type enzyme, but has no observable effect on the enzyme activity. Here, we assess whether a pH effect on the enzyme's conformation is sufficient by itself to explain the pH-dependence of the GarTfase reaction. A pH-dependent conformational change is observed between two high-resolution crystal structures of the Glu70Ala mutant GarTfase at pH 3.5 (1.8 A) and 7.5 (1.9 A). Residues 110 to 131 in GarTfase undergo a transformation from a disordered loop at pH 3.5, where the enzyme is inactive, to an ordered loop-helix structure at pH 7.5, where the enzyme is active. The ordering of this flexible loop-helix has a direct effect on catalytic residues in the active site, binding of the folate cofactor and shielding of the active site from solvent. A main-chain carbonyl oxygen atom from Tyr115 in the ordered loop forms a hydrogen bond with His108, and thereby provides electronic and structural stabilization of this key active site residue. Kinetic data indicate that the pKa of His108 is in fact raised to 9. 2. The loop movement can be correlated with elevation of the His pKa, but with further stabilization, probably from Asp144, after the binding of folate cofactor. Leu118, also in the loop, becomes positioned near the p-amino benzoic acid binding site, providing additional hydrophobic interactions with the cofactor 10-formyl tetrahydrofolate. Thus, the pH-dependence of the enzyme activity appears to arise from local active site rearrangements and not from differences due to monomer-dimer association.


  • Organizational Affiliation

    Department of Molecular Biology and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA, 92093-0359, USA.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
GLYCINAMIDE RIBONUCLEOTIDE TRANSFORMYLASE212Escherichia coliMutation(s): 1 
EC: 2.1.2.2
UniProt
Find proteins for P08179 (Escherichia coli (strain K12))
Explore P08179 
Go to UniProtKB:  P08179
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP08179
Sequence Annotations
Expand
  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
PO4
Query on PO4

Download Ideal Coordinates CCD File 
B [auth A]PHOSPHATE ION
O4 P
NBIIXXVUZAFLBC-UHFFFAOYSA-K
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.90 Å
  • R-Value Free: 0.274 
  • R-Value Work: 0.215 
  • R-Value Observed: 0.215 
  • Space Group: P 61 2 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 50.4α = 90
b = 50.4β = 90
c = 275.5γ = 120
Software Package:
Software NamePurpose
X-PLORmodel building
X-PLORrefinement
DENZOdata reduction
SCALEPACKdata scaling
X-PLORphasing

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 1998-08-12
    Type: Initial release
  • Version 1.1: 2008-03-05
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2021-11-03
    Changes: Database references, Derived calculations, Other
  • Version 1.4: 2023-08-09
    Changes: Refinement description
  • Version 1.5: 2024-05-22
    Changes: Data collection