1zk7
From Proteopedia
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Crystal Structure of Tn501 MerA
Overview
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.
About this Structure
1ZK7 is a Single protein structure of sequence from Pseudomonas aeruginosa with SO4, FAD and GOL as ligands. Active as Mercury(II) reductase, with EC number 1.16.1.1 Full crystallographic information is available from OCA.
Reference
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., Ledwidge R, Patel B, Dong A, Fiedler D, Falkowski M, Zelikova J, Summers AO, Pai EF, Miller SM, Biochemistry. 2005 Aug 30;44(34):11402-16. PMID:16114877
Page seeded by OCA on Wed Nov 21 07:30:01 2007
