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Title: Direct Measurement of Mercury(II) Removal from Organomercurial Lyase (MerB) by Tryptophan Fluorescence: NmerA Domain of Coevolved γ-Proteobacterial Mercuric Ion Reductase (MerA) Is More Efficient Than MerA Catalytic Core or Glutathione,

Journal Article · · Biochemistry
DOI:https://doi.org/10.1021/bi100802k· OSTI ID:1038457
 [1];  [1];  [2];  [3]
  1. Department of Pharmaceutical Chemistry
  2. Graduate Group in Biophysics
  3. Department of Pharmaceutical Chemistry;Graduate Group in Biophysics
+ Show Author Affiliations

Aerobic and facultative bacteria and archaea harboring mer loci exhibit resistance to the toxic effects of Hg(II) and organomercurials [RHg(I)]. In broad spectrum resistance, RHg(I) is converted to less toxic Hg(0) in the cytosol by the sequential action of organomercurial lyase (MerB: RHg(I) → RH + Hg(II)) and mercuric ion reductase (MerA: Hg(II) → Hg(0)) enzymes, requiring transfer of Hg(II) from MerB to MerA. Although previous studies with γ-proteobacterial versions of MerA and a nonphysiological Hg(II)-DTT-MerB complex qualitatively support a pathway for direct transfer between proteins, assessment of the relative efficiencies of Hg(II) transfer to the two different dicysteine motifs in γ-proteobacterial MerA and to competing cellular thiol is lacking. Here we show the intrinsic tryptophan fluorescence of γ-proteobacterial MerB is sensitive to Hg(II) binding and use this to probe the kinetics of Hg(II) removal from MerB by the N-terminal domain (NmerA) and catalytic core C-terminal cysteine pairs of its coevolved MerA and by glutathione (GSH), the major competing cellular thiol in γ-proteobacteria.

Research Organization:
Univ. of California, San Francisco, CA (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Biological and Environmental Research (BER)
DOE Contract Number:
FG02-05ER64120
OSTI ID:
1038457
Report Number(s):
DOE/ER/64120-P1
Journal Information:
Biochemistry, Vol. 49, Issue 37; ISSN 0006-2960
Publisher:
American Chemical Society (ACS)
Country of Publication:
United States
Language:
English

References (37)

The Chemical Cycle and Bioaccumulation of Mercury journal November 1998
The Toxicology of Mercury and Its Chemical Compounds journal January 2006
Mercury(II) complexes with sulfhydryl containing chelating agents: Stability constant inconsistencies and their resolution journal January 1980
Nuclear magnetic resonance studies of the solution chemistry of metal complexes. 25. Hg(thiol)3 complexes and HG(II)-thiol ligand exchange kinetics journal September 1988
Handling of cysteine S-conjugates of methylmercury in MDCK cells expressing human OAT1 journal October 2005
Human organic anion transporter 1 mediates cellular uptake of cysteine-S conjugates of inorganic mercury journal July 2004
Bacterial mercury resistance from atoms to ecosystems journal June 2003
Bacterial resistance to mercury — reductio ad absurdum? journal October 1985
An NMR Study of the Interaction of the N-terminal Cytoplasmic Tail of the Wilson Disease Protein with Copper(I)-HAH1 journal January 2009
Mechanism of Cu+-transporting ATPases: Soluble Cu+ chaperones directly transfer Cu+ to transmembrane transport sites journal April 2008
Function, Structure, and Mechanism of Intracellular Copper Trafficking Proteins journal June 2001
NmerA of Tn 501 Mercuric Ion Reductase: Structural Modulation of the p K a Values of the Metal Binding Cysteine Thiols, journal October 2010
NmerA, the Metal Binding Domain of Mercuric Ion Reductase, Removes Hg 2+ from Proteins, Delivers It to the Catalytic Core, and Protects Cells under Glutathione-Depleted Conditions , journal August 2005
Direct Monitoring of Metal Ion Transfer between Two Trafficking Proteins journal August 2005
Is the cytoplasmic loop of MerT, the mercuric ion transport protein, involved in mercury transfer to the mercuric reductase? journal September 2004
Evidence for direct interactions between the mercuric ion transporter (MerT) and mercuric reductase (MerA) from the Tn501 mer operon journal April 2007
The mercuric and organomercurial detoxifying enzymes from a plasmid-bearing strain of Escherichia coli. journal June 1978
A Stable Mercury-Containing Complex of the Organomercurial Lyase MerB:  Catalysis, Product Release, and Direct Transfer to MerA † journal July 2004
Biophysical characterization of the MerP-like amino-terminal extension of the mercuric reductase from Ralstonia metallidurans CH34 journal November 2003
Cloning and DNA sequence of the mercuric- and organomercurial-resistance determinants of plasmid pDU1358. journal May 1987
Mechanistic studies of a protonolytic organomercurial cleaving enzyme: bacterial organomercurial lyase journal November 1986
Bacterial organomercurial lyase: overproduction, isolation, and characterization journal November 1986
NMR Structural Studies Reveal a Novel Protein Fold for MerB, the Organomercurial Lyase Involved in the Bacterial Mercury Resistance System † , ‡ journal July 2004
Crystal Structures of the Organomercurial Lyase MerB in Its Free and Mercury-bound Forms: INSIGHTS INTO THE MECHANISM OF METHYLMERCURY DEGRADATION journal November 2008
The Roles of Thiols in the Bacterial Organomercurial Lyase (MerB) † journal August 2002
Mercuric reductase. Purification and characterization of a transposon-encoded flavoprotein containing an oxidation-reduction-active disulfide. journal March 1982
Evidence for the participation of Cys558 and Cys559 at the active site of mercuric reductase journal February 1989
Determination of dissociation constants and specific rate constants of enzyme-substrate (or protein-ligand) interactions from rapid reaction kinetic data journal June 1975
Volatilisation of mercury and organomercurials determined by inducible R-factor systems in enteric bacteria journal September 1974
Physical and genetic map of the organomercury resistance (Omr) and inorganic mercury resistance (Hgr) loci of the IncM plasmid R831b journal December 1984
Organization, Expression, and Evolution of Genes for Mercury Resistance journal October 1986
Deoxyribonucleic acid sequence of a gene from the Pseudomonas transposon TN501 encoding mercuric reductase journal August 1983
Alternative Routes for Entry of HgX 2 into the Active Site of Mercuric Ion Reductase Depend on the Nature of the X Ligands † journal March 1999
The Many Faces of Glutathione in Bacteria journal May 2006
Studies on Hg(II)-induced H2O2 formation and oxidative stress in vivo and in vitro in rat kidney mitochondria journal April 1993
Cloning and DNA sequence analysis of the mercury resistance genes of Streptomyces lividans journal December 1992
Distribution of thiols in microorganisms: mycothiol is a major thiol in most actinomycetes journal April 1996

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