1S6L

Solution structure of MerB, the Organomercurial Lyase involved in the bacterial mercury resistance system

Summary for 1S6L

• Entry DOI: 10.2210/pdb1s6l/pdb
• NMR Information: BMRB: 6047
• Descriptor: Alkylmercury lyase (1 entity in total)
• Functional Keywords: lyase
• Biological source: Escherichia coli
• Total number of polymer chains: 1
• Total formula weight: 23058.27

Authors

Di Lello, P.,Benison, G.C.,Valafar, H.,Pitts, K.E.,Summers, A.O.,Legault, P.,Omichinski, J.G. (deposition date: 2004-01-25, release date: 2005-04-19, Last modification date: 2024-05-01)

Primary citation

Di Lello, P.,Benison, G.C.,Valafar, H.,Pitts, K.E.,Summers, A.O.,Legault, P.,Omichinski, J.G.
NMR structural studies reveal a novel protein fold for MerB, the organomercurial lyase involved in the bacterial mercury resistance system.
Biochemistry, 43:8322-8332, 2004

PubMed Abstract: Mercury resistant bacteria have developed a system of two enzymes (MerA and MerB), which allows them to efficiently detoxify both ionic and organomercurial compounds. The organomercurial lyase (MerB) catalyzes the protonolysis of the carbon-mercury bond resulting in the formation of ionic mercury and a reduced hydrocarbon. The ionic mercury [Hg(II)] is subsequently reduced to the less reactive elemental mercury [Hg(0)] by a specific mercuric reductase (MerA). To better understand MerB's unique enzymatic activity, we used nuclear magnetic resonance (NMR) spectroscopy to determine the structure of the free enzyme. MerB is characterized by a novel protein fold consisting of three noninteracting antiparallel beta-sheets surrounded by six alpha-helices. By comparing the NMR data of free MerB and the MerB/Hg/DTT complex, we identified a set of residues that likely define a Hg/DTT binding site. These residues cluster around two cysteines (C(96) and C(159)) that are crucial to MerB's catalytic activity. A detailed analysis of the structure revealed the presence of an extensive hydrophobic groove adjacent to this Hg/DTT binding site. This extensive hydrophobic groove has the potential to interact with the hydrocarbon moiety of a wide variety of substrates and may explain the broad substrate specificity of MerB.

PubMed: 15222745
DOI: 10.1021/bi049669z

Experimental method

SOLUTION NMR