Co-crystal structure of E.coli RNase HI active site mutant (E48A*) with Mn2+

Experimental Data Snapshot

  • Resolution: 2.30 Å
  • R-Value Free: 0.288 
  • R-Value Work: 0.230 

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Identification of Single Mn(2+) Binding Sites Required for Activation of the Mutant Proteins of E.coli RNase HI at Glu48 and/or Asp134 by X-ray Crystallography

Tsunaka, Y.Takano, K.Matsumura, H.Yamagata, Y.Kanaya, S.

(2005) J Mol Biol 345: 1171-1183

  • DOI: https://doi.org/10.1016/j.jmb.2004.11.007
  • Primary Citation of Related Structures:  
    1WSE, 1WSF, 1WSG

  • PubMed Abstract: 

    Escherichia coli RNase HI has two Mn(2+)-binding sites. Site 1 is formed by Asp10, Glu48, and Asp70, and site 2 is formed by Asp10 and Asp134. Site 1 and site 2 have been proposed to be an activation site and an attenuation site, respectively. However, Glu48 and Asp134 are dispensable for Mn(2+)-dependent activity. In order to identify the Mn(2+)-binding sites of the mutant proteins at Glu48 and/or Asp134, the crystal structures of the mutant proteins E48A-RNase HI*, D134A-RNase HI*, and E48A/D134N-RNase HI* in complex with Mn(2+) were determined. In E48A-RNase HI*, Glu48 and Lys87 are replaced by Ala. In D134A-RNase HI*, Asp134 and Lys87 are replaced by Ala. In E48A/D134N-RNase HI*, Glu48 and Lys87 are replaced by Ala and Asp134 is replaced by Asn. All crystals had two or four protein molecules per asymmetric unit and at least two of which had detectable manganese ions. These structures indicated that only one manganese ion binds to the various positions around the center of the active-site pocket. These positions are different from one another, but none of them is similar to site 1. The temperature factors of these manganese ions were considerably larger than those of the surrounding residues. These results suggest that the first manganese ion required for activation of the wild-type protein fluctuates among various positions around the center of the active-site pockets. We propose that this fluctuation is responsible for efficient hydrolysis of the substrates by the protein (metal fluctuation model). The binding position of the first manganese ion is probably forced to shift to site 1 or site 2 upon binding of the second manganese ion.

  • Organizational Affiliation

    Department of Material and Life Science, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka 565-0871, Japan.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Ribonuclease HI
A, B
155Escherichia coliMutation(s): 2 
Find proteins for P0A7Y4 (Escherichia coli (strain K12))
Explore P0A7Y4 
Go to UniProtKB:  P0A7Y4
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP0A7Y4
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 1 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Query on MN

Download Ideal Coordinates CCD File 
C [auth A],
D [auth B]
Experimental Data & Validation

Experimental Data

  • Resolution: 2.30 Å
  • R-Value Free: 0.288 
  • R-Value Work: 0.230 
  • Space Group: P 2 2 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 58.041α = 90
b = 66.008β = 90
c = 79.485γ = 90
Software Package:
Software NamePurpose

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2005-02-08
    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: 2021-11-10
    Changes: Database references, Derived calculations