PDBsum entry 1zk7

Oxidoreductase

PDB id: 1zk7

Contents

Protein chain

467 a.a. *

Ligands

SO4 ×3

FAD

GOL ×3

Waters ×508

* Residue conservation analysis

PDB id:

1zk7

Name:

Oxidoreductase

Title:

Crystal structure of tn501 mera

Structure:

Mercuric reductase. Chain: a. Synonym: hgii, reductase. Engineered: yes

Source:

Pseudomonas aeruginosa. Organism_taxid: 287. Gene: mera. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.

Biol. unit:

Dimer (from PDB file)

Resolution:

1.60Å R-factor: 0.192 R-free: 0.212

Authors:

A.Dong,R.Ledwidge,B.Patel,D.Fiedler,M.Falkowski,J.Zelikova, A.O.Summers,E.F.Pai,S.M.Miller

Key ref:

R.Ledwidge et al. (2005). NmerA, the metal binding domain of mercuric ion reductase, removes Hg2+ from proteins, delivers it to the catalytic core, and protects cells under glutathione-depleted conditions. Biochemistry, 44, 11402-11416. PubMed id: 16114877 DOI: 10.1021/bi050519d

Date:

02-May-05 Release date: 05-Jul-05

Protein chain

P00392  (MERA_PSEAI) -  Mercuric reductase from Pseudomonas aeruginosa

Seq: 561 a.a.

Struc: 467 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

Enzyme reactions

• Enzyme class: E.C.1.16.1.1 - mercury(II) reductase.
• Reaction: Hg + NADP⁺ + H⁺ = Hg²⁺ + NADPH

Hg + NADP(+) + H(+) (Bound ligand (Het Group name = FAD) matches with 71.19% similarity) = Hg(2+) + NADPH

Molecule diagrams generated from .mol files obtained from the KEGG ftp site

Added reference

DOI no: 10.1021/bi050519d

Biochemistry 44:11402-11416 (2005)

PubMed id: 16114877

NmerA, the metal binding domain of mercuric ion reductase, removes Hg2+ from proteins, delivers it to the catalytic core, and protects cells under glutathione-depleted conditions.

R.Ledwidge, B.Patel, A.Dong, D.Fiedler, M.Falkowski, J.Zelikova, A.O.Summers, E.F.Pai, S.M.Miller.

ABSTRACT

The ligand binding and catalytic properties of heavy metal ions have led to the evolution of metal ion-specific pathways for control of their intracellular trafficking and/or elimination. Small MW proteins/domains containing a GMTCXXC metal binding motif in a betaalphabetabetaalphabeta fold are common among proteins controlling the mobility of soft metal ions such as Cu(1+), Zn(2+), and Hg(2+), and the functions of several have been established. In bacterial mercuric ion reductases (MerA), which catalyze reduction of Hg(2+) to Hg(0) as a means of detoxification, one or two repeats of sequences with this fold are highly conserved as N-terminal domains (NmerA) of uncertain function. To simplify functional analysis of NmerA, we cloned and expressed the domain and catalytic core of Tn501 MerA as separate proteins. In this paper, we show Tn501 NmerA to be a stable, soluble protein that binds 1 Hg(2+)/domain and delivers it to the catalytic core at kinetically competent rates. Comparison of steady-state data for full-length versus catalytic core MerA using Hg(glutathione)(2) or Hg(thioredoxin) as substrate demonstrates that the NmerA domain does participate in acquisition and delivery of Hg(2+) to the catalytic core during the reduction catalyzed by full-length MerA, particularly when Hg(2+) is bound to a protein. Finally, comparison of growth curves for glutathione-depleted Escherichia coli expressing either catalytic core, full-length, or a combination of core plus NmerA shows an increased protection of cells against Hg(2+) in the media when NmerA is present, providing the first evidence of a functional role for this highly conserved domain.