3F2G

Crystal structure of MerB mutant C160S, the Organomercurial Lyase involved in a bacterial mercury resistance system


Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.781 Å
  • R-Value Free: 0.223 
  • R-Value Work: 0.185 

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This is version 1.1 of the entry. See complete history

Literature

Crystal Structures of the Organomercurial Lyase MerB in Its Free and Mercury-bound Forms: INSIGHTS INTO THE MECHANISM OF METHYLMERCURY DEGRADATION

Lafrance-Vanasse, J.Lefebvre, M.Di Lello, P.Sygusch, J.Omichinski, J.G.

(2009) J.Biol.Chem. 284: 938-944

  • DOI: 10.1074/jbc.M807143200
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 
  • Bacteria resistant to methylmercury utilize two enzymes (MerA and MerB) to degrade methylmercury to the less toxic elemental mercury. The crucial step is the cleavage of the carbon-mercury bond of methylmercury by the organomercurial lyase (MerB). In ...

    Bacteria resistant to methylmercury utilize two enzymes (MerA and MerB) to degrade methylmercury to the less toxic elemental mercury. The crucial step is the cleavage of the carbon-mercury bond of methylmercury by the organomercurial lyase (MerB). In this study, we determined high resolution crystal structures of MerB in both the free (1.76-A resolution) and mercury-bound (1.64-A resolution) states. The crystal structure of free MerB is very similar to the NMR structure, but important differences are observed when comparing the two structures. In the crystal structure, an amino-terminal alpha-helix that is not present in the NMR structure makes contact with the core region adjacent to the catalytic site. This interaction between the amino-terminal helix and the core serves to bury the active site of MerB. The crystal structures also provide detailed insights into the mechanism of carbon-mercury bond cleavage by MerB. The structures demonstrate that two conserved cysteines (Cys-96 and Cys-159) play a role in substrate binding, carbon-mercury bond cleavage, and controlled product (ionic mercury) release. In addition, the structures establish that an aspartic acid (Asp-99) in the active site plays a crucial role in the proton transfer step required for the cleavage of the carbon-mercury bond. These findings are an important step in understanding the mechanism of carbon-mercury bond cleavage by MerB.


    Organizational Affiliation

    Department of Biochemistry, Université de Montréal, Montréal, Québec H3C 3J7, Canada.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Alkylmercury lyase
A, B
220Escherichia coliMutation(s): 1 
Gene Names: merB
EC: 4.99.1.2
Find proteins for P77072 (Escherichia coli)
Go to UniProtKB:  P77072
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 1.781 Å
  • R-Value Free: 0.223 
  • R-Value Work: 0.185 
  • Space Group: P 1 21 1
Unit Cell:
Length (Å)Angle (°)
a = 38.835α = 90.00
b = 89.113β = 97.47
c = 54.722γ = 90.00
Software Package:
Software NamePurpose
HKL-2000data scaling
CBASSdata collection
HKL-2000data reduction
PHENIXphasing
PHENIXmodel building
PHENIXrefinement

Structure Validation

View Full Validation Report or Ramachandran Plots



Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2008-11-11
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Version format compliance