1F21

DIVALENT METAL COFACTOR BINDING IN THE KINETIC FOLDING TRAJECTORY OF E. COLI RIBONUCLEASE HI


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.40 Å
  • R-Value Free: 0.254 
  • R-Value Work: 0.217 

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This is version 1.2 of the entry. See complete history


Literature

Divalent metal cofactor binding in the kinetic folding trajectory of Escherichia coli ribonuclease HI.

Goedken, E.R.Keck, J.L.Berger, J.M.Marqusee, S.

(2000) Protein Sci 9: 1914-1921

  • DOI: 10.1110/ps.9.10.1914
  • Primary Citation of Related Structures:  
    1F21

  • PubMed Abstract: 
  • Proteins often require cofactors to perform their biological functions and must fold in the presence of their cognate ligands. Using circular dichroism spectroscopy. we investigated the effects of divalent metal binding upon the folding pathway of Escherichia coli RNase HI ...

    Proteins often require cofactors to perform their biological functions and must fold in the presence of their cognate ligands. Using circular dichroism spectroscopy. we investigated the effects of divalent metal binding upon the folding pathway of Escherichia coli RNase HI. This enzyme binds divalent metal in its active site, which is proximal to the folding core of RNase HI as defined by hydrogen/deuterium exchange studies. Metal binding increases the apparent stability of native RNase HI chiefly by reducing the unfolding rate. As with the apo-form of the protein, refolding from high denaturant concentrations in the presence of Mg2+ follows three-state kinetics: formation of a rapid burst phase followed by measurable single exponential kinetics. Therefore, the overall folding pathway of RNase HI is minimally perturbed by the presence of metal ions. Our results indicate that the metal cofactor enters the active site pocket only after the enzyme reaches its native fold, and therefore, divalent metal binding stabilizes the protein by decreasing its unfolding rate. Furthermore, the binding of the cofactor is dependent upon a carboxylate critical for activity (Asp10). A mutation in this residue (D10A) alters the folding kinetics in the absence of metal ions such that they are similar to those observed for the unaltered enzyme in the presence of metal.


    Organizational Affiliation

    Department of Molecular and Cell Biology, University of California, Berkeley 94720, USA.



Macromolecules
Find similar proteins by:  (by identity cutoff)  |  Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
RIBONUCLEASE HIA155Escherichia coliMutation(s): 3 
EC: 3.1.26.4
UniProt
Find proteins for P0A7Y4 (Escherichia coli (strain K12))
Explore P0A7Y4 
Go to UniProtKB:  P0A7Y4
Protein Feature View
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  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.40 Å
  • R-Value Free: 0.254 
  • R-Value Work: 0.217 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 37.27α = 90
b = 40.83β = 90
c = 85.45γ = 90
Software Package:
Software NamePurpose
AMoREphasing
REFMACrefinement
DENZOdata reduction
SCALEPACKdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2000-12-06
    Type: Initial release
  • Version 1.1: 2008-04-27
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance