Structure and function of YghU, a nu-class glutathione transferase related to YfcG from Escherichia coli.

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TitleStructure and function of YghU, a nu-class glutathione transferase related to YfcG from Escherichia coli.
Publication TypeJournal Article
Year of Publication2011
AuthorsStourman, NV, Branch, MC, Schaab, MR, Harp, JM, Ladner, JE, Armstrong, RN
JournalBiochemistry
Volume50
Issue7
Pagination1274-81
Date Published2011 Feb 22
ISSN1520-4995
KeywordsCloning, Molecular, Crystallography, X-Ray, Escherichia coli, Escherichia coli Proteins, Glutathione Transferase, Models, Biological, Models, Molecular, Molecular Dynamics Simulation, Multigene Family, Phylogeny, Protein Structure, Secondary, Sequence Homology
Abstract

The crystal structure (1.50 Å resolution) and biochemical properties of the GSH transferase homologue, YghU, from Escherichia coli reveal that the protein is unusual in that it binds two molecules of GSH in each active site. The crystallographic observation is consistent with biphasic equilibrium binding data that indicate one tight (K(d1) = 0.07 ± 0.03 mM) and one weak (K(d2) = 1.3 ± 0.2 mM) binding site for GSH. YghU exhibits little or no GSH transferase activity with most typical electrophilic substrates but does possess a modest catalytic activity toward several organic hydroperoxides. Most notably, the enzyme also exhibits disulfide-bond reductase activity toward 2-hydroxyethyl disulfide [k(cat) = 74 ± 6 s(-1), and k(cat)/K(M)(GSH) = (6.6 ± 1.3) × 10(4) M(-1) s(-1)] that is comparable to that previously determined for YfcG. A superposition of the structures of the YghU·2GSH and YfcG·GSSG complexes reveals a remarkable structural similarity of the active sites and the 2GSH and GSSG molecules in each. We conclude that the two structures represent reduced and oxidized forms of GSH-dependent disulfide-bond oxidoreductases that are distantly related to glutaredoxin 2. The structures and properties of YghU and YfcG indicate that they are members of the same, but previously unidentified, subfamily of GSH transferase homologues, which we suggest be called the nu-class GSH transferases.

DOI10.1021/bi101861a
Alternate JournalBiochemistry
PubMed ID21222452
PubMed Central IDPMC3040281
Grant ListP30 ES000267 / ES / NIEHS NIH HHS / United States
P30 ES000267-37 / ES / NIEHS NIH HHS / United States
R01 GM030910 / GM / NIGMS NIH HHS / United States
R01 GM030910-28 / GM / NIGMS NIH HHS / United States
R01 GM030910-29 / GM / NIGMS NIH HHS / United States
T32 ES007028 / ES / NIEHS NIH HHS / United States
T32 GM065086 / GM / NIGMS NIH HHS / United States
T32 GM065086-07S1 / GM / NIGMS NIH HHS / United States
U54 GM093342-01 / GM / NIGMS NIH HHS / United States
U54 GM093342-01 / GM / NIGMS NIH HHS / United States