2P7S

Enzymatic and Structural Characterisation of Amphinase, a Novel Cytotoxic Ribonuclease from Rana pipiens Oocytes


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.8 Å
  • R-Value Free: 0.241 
  • R-Value Work: 0.221 

wwPDB Validation 3D Report Full Report


This is version 1.3 of the entry. See complete history

Literature

Enzymatic and Structural Characterisation of Amphinase, a Novel Cytotoxic Ribonuclease from Rana pipiens Oocytes.

Singh, U.P.Ardelt, W.Saxena, S.K.Holloway, D.E.Vidunas, E.Lee, H.S.Saxena, A.Shogen, K.Acharya, K.R.

(2007) J.Mol.Biol. 371: 93-111

  • DOI: 10.1016/j.jmb.2007.04.071
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • Besides Onconase (ONC) and its V11/N20/R103-variant, oocytes of the Northern Leopard frog (Rana pipiens) contain another homologue of ribonuclease A, which we named Amphinase (Amph). Four variants (Amph-1-4) were isolated and sequenced, each 114 amin ...

    Besides Onconase (ONC) and its V11/N20/R103-variant, oocytes of the Northern Leopard frog (Rana pipiens) contain another homologue of ribonuclease A, which we named Amphinase (Amph). Four variants (Amph-1-4) were isolated and sequenced, each 114 amino acid residues in length and N-glycosylated at two positions. Sequence identities (a) among the variants and (b) versus ONC are 86.8-99.1% and 38.2-40.0%, respectively. When compared with other amphibian ribonucleases, a typical pattern of cysteine residues is evident but the N-terminal pyroglutamate residue is replaced by a six-residue extension. Amph variants have relatively weak ribonucleolytic activity that is insensitive to human ribonuclease inhibitor protein (RI). Values of k(cat)/K(M) with hypersensitive fluorogenic substrates are 10(4) and 10(2)-fold lower than the maximum values exhibited by ribonuclease A and ONC, respectively, and there is little cytosine/uracil or adenine/guanine discrimination at the B(1) or B(2) subsites, respectively. Amph variants have cytotoxic activity toward A-253 carcinoma cells that requires intact ribonucleolytic activity. The glycan component has little or no influence over single-stranded RNA cleavage, RI evasion or cytotoxicity. The crystal structures of natural and recombinant Amph-2 (determined at 1.8 and 1.9 A resolution, respectively) reveal that the N terminus is unlikely to play a catalytic role (but an unusual alpha2-beta1 loop may do so) and the B(2) subsite is rudimentary. At the active site, structural features that may contribute to the enzyme's low ribonucleolytic activity are the fixture of Lys14 in an obstructive position, the accompanying ejection of Lys42, and a lack of constraints on the conformations of Lys42 and His107.


    Organizational Affiliation

    Department of Biology and Biochemistry, University of Bath, Claverton Down, Bath BA2 7AY, UK.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Amphinase-2
A
114Lithobates pipiensMutation(s): 0 
EC: 3.1.27.-
Find proteins for P85073 (Lithobates pipiens)
Go to UniProtKB:  P85073
Small Molecules
Ligands 3 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
ACT
Query on ACT

Download SDF File 
Download CCD File 
A
ACETATE ION
C2 H3 O2
QTBSBXVTEAMEQO-UHFFFAOYSA-M
 Ligand Interaction
GOL
Query on GOL

Download SDF File 
Download CCD File 
A
GLYCEROL
GLYCERIN; PROPANE-1,2,3-TRIOL
C3 H8 O3
PEDCQBHIVMGVHV-UHFFFAOYSA-N
 Ligand Interaction
NAG
Query on NAG

Download SDF File 
Download CCD File 
A
N-ACETYL-D-GLUCOSAMINE
C8 H15 N O6
OVRNDRQMDRJTHS-FMDGEEDCSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.8 Å
  • R-Value Free: 0.241 
  • R-Value Work: 0.221 
  • Space Group: P 41
Unit Cell:
Length (Å)Angle (°)
a = 53.967α = 90.00
b = 53.967β = 90.00
c = 47.796γ = 90.00
Software Package:
Software NamePurpose
HKL-2000data reduction
SCALEPACKdata scaling
AMoREphasing
PDB_EXTRACTdata extraction
CNSrefinement
DENZOdata reduction

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

  • Deposited Date: 2007-03-20 
  • Released Date: 2007-05-29 
  • Deposition Author(s): Singh, U.P.

Revision History 

  • Version 1.0: 2007-05-29
    Type: Initial release
  • Version 1.1: 2008-05-01
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Non-polymer description, Version format compliance
  • Version 1.3: 2017-10-18
    Type: Refinement description