3BJ7

Spermine/spermidine N1-acetyltransferase from mouse: Crystal structure of a ternary complex reveals solvent-mediated spermine binding


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.2 Å
  • R-Value Free: 0.294 
  • R-Value Work: 0.231 

wwPDB Validation 3D Report Full Report


This is version 1.1 of the entry. See complete history

Literature

The crystal structure of spermidine/spermine N1-acetyltransferase in complex with spermine provides insights into substrate binding and catalysis.

Montemayor, E.J.Hoffman, D.W.

(2008) Biochemistry 47: 9145-9153

  • DOI: 10.1021/bi8009357
  • Primary Citation of Related Structures:  3BJ8

  • PubMed Abstract: 
  • The enzyme spermidine/spermine N (1)-acetyltransferase (SSAT) catalyzes the transfer of acetyl groups from acetylcoenzyme A to spermidine and spermine, as part of a polyamine degradation pathway. This work describes the crystal structure of SSAT in c ...

    The enzyme spermidine/spermine N (1)-acetyltransferase (SSAT) catalyzes the transfer of acetyl groups from acetylcoenzyme A to spermidine and spermine, as part of a polyamine degradation pathway. This work describes the crystal structure of SSAT in complex with coenzyme A, with and without bound spermine. The complex with spermine provides a direct view of substrate binding by an SSAT and demonstrates structural plasticity near the active site of the enzyme. Associated water molecules bridge several of the intermolecular contacts between spermine and the enzyme and form a "proton wire" between the side chain of Glu92 and the N1 amine of spermine. A single water molecule can also be seen forming hydrogen bonds with the side chains of Glu92, Asp93, and the N4 amine of spermine. Site-directed mutation of Glu92 to glutamine had a detrimental effect on both substrate binding and catalysis and shifted the optimal pH for enzyme activity further into alkaline solution conditions, while mutation of Asp93 to asparagine affected both substrate binding and catalysis without changing the pH dependence of the enzyme. Considered together, the structural and kinetic data suggest that Glu92 functions as a catalytic base to drive an otherwise unfavorable deprotonation step at physiological pH.


    Organizational Affiliation

    Department of Chemistry and Biochemistry, Institute for Cellular and Molecular Biology, University of Texas, Austin, Texas 78712, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Diamine acetyltransferase 1
A, B, C, D
171Mus musculusGene Names: Sat1 (Sat)
EC: 2.3.1.57
Find proteins for P48026 (Mus musculus)
Go to UniProtKB:  P48026
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
COA
Query on COA

Download SDF File 
Download CCD File 
A, B, C, D
COENZYME A
C21 H36 N7 O16 P3 S
RGJOEKWQDUBAIZ-IBOSZNHHSA-N
 Ligand Interaction
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.2 Å
  • R-Value Free: 0.294 
  • R-Value Work: 0.231 
  • Space Group: P 21 21 21
Unit Cell:
Length (Å)Angle (°)
a = 76.857α = 90.00
b = 97.191β = 90.00
c = 105.698γ = 90.00
Software Package:
Software NamePurpose
CNSrefinement
CNSphasing
HKL-2000data reduction
HKL-2000data scaling

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

  • Deposited Date: 2007-12-03 
  • Released Date: 2008-09-16 
  • Deposition Author(s): Montemayor, E.J.

Revision History 

  • Version 1.0: 2008-09-16
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Version format compliance