Crystal Structure of AqpZ mutant L170C complexed with mercury.

Experimental Data Snapshot

  • Resolution: 1.90 Å
  • R-Value Free: 0.195 
  • R-Value Work: 0.166 
  • R-Value Observed: 0.167 

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Structural basis of aquaporin inhibition by mercury.

Savage, D.F.Stroud, R.M.

(2007) J Mol Biol 368: 607-617

  • DOI: https://doi.org/10.1016/j.jmb.2007.02.070
  • Primary Citation of Related Structures:  
    2O9D, 2O9E, 2O9F, 2O9G

  • PubMed Abstract: 

    The aquaporin family of channels was defined based on the inhibition of water transport by mercurial compounds. Despite the important role of mercurials, little is known about the structural changes involved upon mercury binding leading to channel inhibition. To elucidate the mechanism we designed a mutant, T183C, of aquaporin Z (AqpZ) patterned after the known mercury-sensitive site of aquaporin 1 (AQP1) and determined the X-ray crystal structures of the unbound and mercury blocked states. Superposition of the two structures shows no conformational rearrangement upon mercury binding. In the blocked structure, there are two mercury sites, one bound to Cys183 and occluding the pore, and a second, also bound to the same cysteine but found buried in an interstitial cavity. To test the mechanism of blockade we designed a different mutant, L170C, to produce a more effective mercury block at the pore site. In a dose-response inhibition study, this mutant was 20 times more sensitive to mercury than wild-type AqpZ and four times more sensitive than T183C. The X-ray structure of L170C shows four mercury atoms at, or near, the pore site defined in the T183C structure and no structural change upon mercury binding. Thus, we elucidate a steric inhibition mechanism for this important class of channels by mercury.

  • Organizational Affiliation

    Graduate Group in Biophysics, University of California at San Francisco, San Francisco, CA 94158, USA. savage@msg.ucsf.edu

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Aquaporin Z234Escherichia coliMutation(s): 3 
Gene Names: aqpZbniP
Membrane Entity: Yes 
Find proteins for P60844 (Escherichia coli (strain K12))
Explore P60844 
Go to UniProtKB:  P60844
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP60844
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 1.90 Å
  • R-Value Free: 0.195 
  • R-Value Work: 0.166 
  • R-Value Observed: 0.167 
  • Space Group: I 4
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 91.156α = 90
b = 91.156β = 90
c = 77.145γ = 90
Software Package:
Software NamePurpose
SCALAdata scaling
PDB_EXTRACTdata extraction
CCP4data scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2007-02-13
    Type: Initial release
  • Version 1.1: 2008-05-01
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Derived calculations, Version format compliance
  • Version 1.3: 2020-07-29
    Type: Remediation
    Reason: Carbohydrate remediation
    Changes: Advisory, Data collection, Database references, Derived calculations, Structure summary
  • Version 1.4: 2021-10-20
    Changes: Advisory, Database references, Structure summary
  • Version 1.5: 2023-12-27
    Changes: Data collection