1XWF

K185N mutated S-adenosylhomocysteine hydrolase


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.80 Å
  • R-Value Free: 0.286 
  • R-Value Work: 0.225 
  • R-Value Observed: 0.226 

wwPDB Validation   3D Report Full Report


This is version 1.3 of the entry. See complete history


Literature

Catalytic mechanism of S-adenosylhomocysteine hydrolase: Roles of His 54, Asp130, Glu155, Lys185, and Aspl89.

Yamada, T.Takata, Y.Komoto, J.Gomi, T.Ogawa, H.Fujioka, M.Takusagawa, F.

(2005) Int J Biochem Cell Biol 37: 2417-2435

  • DOI: 10.1016/j.biocel.2005.06.009
  • Primary Citation of Related Structures:  
    1XWF

  • PubMed Abstract: 
  • S-adenosylhomocysteine hydrolase (AdoHcyase) catalyzes the hydrolysis of S-adenosylhomocysteine (AdoHcy) to form adenosine and homocysteine. The crystal structure of the K185N mutated enzyme, which has weak catalytic activity (0.1%), has been determined at 2 ...

    S-adenosylhomocysteine hydrolase (AdoHcyase) catalyzes the hydrolysis of S-adenosylhomocysteine (AdoHcy) to form adenosine and homocysteine. The crystal structure of the K185N mutated enzyme, which has weak catalytic activity (0.1%), has been determined at 2.8 A resolution and supports the previously predicted mechanism [Takata, Y., Yamada, T., Huang, Y., Komoto, J., Gomi, T., Ogawa, H., Fujioka, M., & Takusagawa, F. (2002). Catalytic mechanism of S-adenosylhomocysteine hydrolase. Site-directed mutagenesis of Asp-130, Lys-185, Asp-189, and Asn-190. J. Biol. Chem. 277, 22670-22676]. The mutated enzyme has an intermediate structure between the open and closed conformation, observed in the substrate-free enzyme and in the inhibitor complexes, respectively. H54, H300, and H352 were mutated to asparagine, respectively, to identify the roles of the histidine residues in catalysis. The kinetic data of H54N, H300N, and H354N mutated enzymes suggest that H54 is the amino acid residue that acts as a general acid/base to cleave the C5'-S(D) bond of AdoHcy. The E155Q mutated enzyme retained a large portion of the catalytic activity (31%), while the E155D mutated enzyme lost most of it (0.3%). The NADH accumulation measurements of the mutated enzymes indicated that the C3'-oxidation and the C4'-proton abstraction are a concerted event and the C5'-S(D) bond cleavage is an independent event. The C4'-proton exchange measurements indicate that the enzyme has an open conformation when AdoHcy is converted to 3'-keto-4', 5'-dehydro-Ado in the active site. With the results of this study and those of the previous studies, a detailed catalytic mechanism of AdoHcyase is described. K185 facilitates the C3'-oxidation, D130 abstracts the C4'-proton, D189, and E155 act as a communicator between the concerted C3'-oxidation and C4'-proton abstraction, and H54 plays as a general acid to cleave the C5'-S(D) bond of AdoHcy.


    Organizational Affiliation

    Department of Molecular Biosciences, 3004 Haworth Hall, University of Kansas, Lawrence, KS 66045-7534, USA.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
AdenosylhomocysteinaseA, B, C, D431Rattus norvegicusMutation(s): 1 
Gene Names: Ahcy
EC: 3.3.1.1
UniProt
Find proteins for P10760 (Rattus norvegicus)
Explore P10760 
Go to UniProtKB:  P10760
Protein Feature View
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.80 Å
  • R-Value Free: 0.286 
  • R-Value Work: 0.225 
  • R-Value Observed: 0.226 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 90.34α = 90
b = 109.37β = 115.5
c = 104.07γ = 90
Software Package:
Software NamePurpose
ASPdata collection
SCALEPACKdata scaling
CNSrefinement
CNSphasing

Structure Validation

View Full Validation Report



Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2005-09-20
    Type: Initial release
  • Version 1.1: 2008-04-30
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2017-10-11
    Changes: Refinement description