1BIR

RIBONUCLEASE T1, PHE 100 TO ALA MUTANT COMPLEXED WITH 2' GMP


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.80 Å
  • R-Value Free: 0.240 
  • R-Value Work: 0.186 
  • R-Value Observed: 0.186 

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This is version 1.4 of the entry. See complete history


Literature

A catalytic function for the structurally conserved residue Phe 100 of ribonuclease T1.

Doumen, J.Gonciarz, M.Zegers, I.Loris, R.Wyns, L.Steyaert, J.

(1996) Protein Sci 5: 1523-1530

  • DOI: https://doi.org/10.1002/pro.5560050808
  • Primary Citation of Related Structures:  
    1BIR

  • PubMed Abstract: 

    The function of the conserved Phe 100 residue of RNase T1 (EC 3.1.27.3) has been investigated by site-directed mutagenesis and X-ray crystallography. Replacement of Phe 100 by alanine results in a mutant enzyme with kcat reduced 75-fold and a small increase in Km for the dinucleoside phosphate substrate GpC. The Phe 100 Ala substitution has similar effects on the turnover rates of GpC and its minimal analogue GpOMe, in which the leaving cytidine is replaced by methanol. The contribution to catalysis is independent of the nature of the leaving group, indicating that Phe 100 belongs to the primary site. The contribution of Phe 100 to catalysis may result from a direct van der Waals contact between its aromatic ring and the phosphate moiety of the substrate. Phe 100 may also contribute to the positioning of the pentacovalent phosphorus of the transition state, relative to other catalytic residues. If compared to the corresponding wild-type data, the structural implications of the mutation in the present crystal structure of Phe 100 Ala RNase T1 complexed with the specific inhibitor 2'-GMP are restricted to the active site. Repositioning of 2'-GMP, caused by the Phe 100 Ala mutation, generates new or improved contacts of the phosphate moiety with Arg 77 and His 92. In contrast, interactions with the Glu 58 carboxylate appear to be weakened. The effects of the His 92 Gln and Phe 100 Ala mutations on GpC turnover are additive in the corresponding double mutant, indicating that the contribution of Phe 100 to catalysis is independent of the catalytic acid His 92. The present results lead to the conclusion that apolar residues may contribute considerably to catalyze conversions of charged molecules to charged products, involving even more polar transition states.


  • Organizational Affiliation

    Dienst Ultrastructuur, Vlaams Interuniversitair Instituut Biotechnologie, Vrije Universiteit Brussel, Sint-Genesius-Rode, Belgium.


Macromolecules
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Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
RIBONUCLEASE T1
A, B
104Aspergillus oryzaeMutation(s): 1 
Gene Names: SYNTHETIC GENE
EC: 3.1.27.3
UniProt
Find proteins for P00651 (Aspergillus oryzae (strain ATCC 42149 / RIB 40))
Explore P00651 
Go to UniProtKB:  P00651
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP00651
Sequence Annotations
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  • Reference Sequence
Small Molecules
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.80 Å
  • R-Value Free: 0.240 
  • R-Value Work: 0.186 
  • R-Value Observed: 0.186 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 49.2α = 90
b = 48.19β = 90.26
c = 40.16γ = 90
Software Package:
Software NamePurpose
MOSFLMdata reduction
X-PLORmodel building
X-PLORrefinement
X-PLORphasing

Structure Validation

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Ligand Structure Quality Assessment 


Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 1996-08-17
    Type: Initial release
  • Version 1.1: 2008-03-24
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2018-03-21
    Changes: Data collection
  • Version 1.4: 2021-11-03
    Changes: Database references, Derived calculations