2JEV

Crystal structure of human spermine,spermidine acetyltransferase in complex with a bisubstrate analog (N1-acetylspermine-S-CoA).


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.3 Å
  • R-Value Free: 0.275 
  • R-Value Work: 0.224 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history

Literature

Mechanistic and Structural Analysis of Human Spermidine/Spermine N(1)-Acetyltransferase.

Hegde, S.S.Chandler, J.Vetting, M.W.Yu, M.Blanchard, J.S.

(2007) Biochemistry 46: 7187

  • DOI: 10.1021/bi700256z

  • PubMed Abstract: 
  • The N1-acetylation of spermidine and spermine by spermidine/spermine acetyltransferase (SSAT) is a crucial step in the regulation of the cellular polyamine levels in eukaryotic cells. Altered polyamine levels are associated with a variety of cancers ...

    The N1-acetylation of spermidine and spermine by spermidine/spermine acetyltransferase (SSAT) is a crucial step in the regulation of the cellular polyamine levels in eukaryotic cells. Altered polyamine levels are associated with a variety of cancers as well as other diseases, and key enzymes in the polyamine pathway, including SSAT, are being explored as potential therapeutic drug targets. We have expressed and purified human SSAT in Escherichia coli and characterized its kinetic and chemical mechanism. Initial velocity and inhibition studies support a random sequential mechanism for the enzyme. The bisubstrate analogue, N1-spermine-acetyl-coenzyme A, exhibited linear, competitive inhibition against both substrates with a true Ki of 6 nM. The pH-activity profile was bell-shaped, depending on the ionization state of two groups exhibiting apparent pKa values of 7.27 and 8.87. The three-dimensional crystal structure of SSAT with bound bisubstrate inhibitor was determined at 2.3 A resolution. The structure of the SSAT-spermine-acetyl-coenzyme A complex suggested that Tyr140 acts as general acid and Glu92, through one or more water molecules, acts as the general base during catalysis. On the basis of kinetic properties, pH dependence, and structural information, we propose an acid/base-assisted reaction catalyzed by SSAT, involving a ternary complex.


    Organizational Affiliation

    Department of Biochemistry, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Bronx, New York 10461, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
DIAMINE ACETYLTRANSFERASE 1
A, B
174Homo sapiensGene Names: SAT1 (SAT)
EC: 2.3.1.57
Find proteins for P21673 (Homo sapiens)
Go to Gene View: SAT1
Go to UniProtKB:  P21673
Small Molecules
Ligands 1 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
NHQ
Query on NHQ

Download SDF File 
Download CCD File 
A, B
(3R)-27-AMINO-3-HYDROXY-2,2-DIMETHYL-4,8,14-TRIOXO-12-THIA-5,9,15,19,24-PENTAAZAHEPTACOS-1-YL [(2S,3R,4S,5S)-5-(6-AMINO-9H-PURIN-9-YL)-4-HYDROXY-3-(PHOSPHONOOXY)TETRAHYDROFURAN-2-YL]METHYL DIHYDROGEN DIPHOSPHATE
N1-ACETYLSPERMINE-S-COA
C33 H62 N11 O17 P3 S
BNNJEDLSMFSIRT-GMHMEAMDSA-N
 Ligand Interaction
External Ligand Annotations 
IDBinding Affinity (Sequence Identity %)
NHQKi: 6 nM BINDINGMOAD
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.3 Å
  • R-Value Free: 0.275 
  • R-Value Work: 0.224 
  • Space Group: P 43
Unit Cell:
Length (Å)Angle (°)
a = 46.729α = 90.00
b = 46.729β = 90.00
c = 191.792γ = 90.00
Software Package:
Software NamePurpose
CCP4data scaling
MOSFLMdata reduction
AMoREphasing
REFMACrefinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2007-06-05
    Type: Initial release
  • Version 1.1: 2011-05-08
    Type: Version format compliance
  • Version 1.2: 2011-07-13
    Type: Version format compliance