1AHC

THE N-GLYCOSIDASE MECHANISM OF RIBOSOME-INACTIVATING PROTEINS IMPLIED BY CRYSTAL STRUCTURES OF ALPHA-MOMORCHARIN


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.00 Å
  • R-Value Work: 0.180 
  • R-Value Observed: 0.180 

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This is version 1.3 of the entry. See complete history


Literature

The N-glycosidase mechanism of ribosome-inactivating proteins implied by crystal structures of alpha-momorcharin.

Ren, J.Wang, Y.Dong, Y.Stuart, D.I.

(1994) Structure 2: 7-16

  • DOI: https://doi.org/10.1016/s0969-2126(00)00004-6
  • Primary Citation of Related Structures:  
    1AHA, 1AHB, 1AHC

  • PubMed Abstract: 

    alpha-Momorcharin (alpha MMC) is a type I ribosome-inactivating protein. It inhibits protein synthesis by hydrolytically removing a specific adenine residue from a highly conserved, single-stranded loop of rRNA. Here we describe the determination and refinement of the crystal structures of alpha MMC in the native state and in complexes with the product, adenine, and a substrate analogue, formycin 5'-monophosphate (FMP) at high resolution. Both adenine and the base of FMP are tightly bound; the ribose of bound FMP adopts a strained, high-energy conformation, which may mimic the structure of the transition state. These structures indicate that residues Tyr70, Glu160 and Arg163 of alpha MMC are the most critical for catalysis. We propose that the strained conformation of the ribose in the target adenosine weakens the glycoside bond. Partial protonation mediated by Arg163 then facilitates N-glycoside bond cleavage, leading to the formation of an oxycarbonium ion intermediate which is stabilized by the negatively-charged Glu160. Tyr70 adopts subtly different conformations in the three structures implying that it may be important in substrate recognition and perhaps catalysis.


  • Organizational Affiliation

    Oxford Centre for Molecular Sciences, UK.


Macromolecules
Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
ALPHA-MOMORCHARIN246Momordica charantiaMutation(s): 0 
EC: 3.2.2.22
UniProt
Find proteins for P16094 (Momordica charantia)
Explore P16094 
Go to UniProtKB:  P16094
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP16094
Sequence Annotations
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.00 Å
  • R-Value Work: 0.180 
  • R-Value Observed: 0.180 
  • Space Group: H 3
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 131.3α = 90
b = 131.3β = 90
c = 40.2γ = 120
Software Package:
Software NamePurpose
X-PLORmodel building
X-PLORrefinement
X-PLORphasing

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 1994-06-22
    Type: Initial release
  • Version 1.1: 2008-03-03
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2024-02-07
    Changes: Data collection, Database references, Other