Redox properties and evolution of human glutaredoxins
2007 (English)In: Proteins: Structure, Function, and Genetics, ISSN 0887-3585, E-ISSN 1097-0134, Vol. 68, no 4, 879-892 p.Article in journal (Refereed) Published
Glutaredoxins (Grxs) are glutathione-dependent oxidoreductases that belong to the thioredoxin superfamily catalyzing thiol-disulfide exchange reactions via active site cysteine residues. Focusing on the human dithiol glutaredoxins having a C-X-Y-C active site sequence motif, the redox potentials of hGrxl and hGrx2 were determined to be -232 and -221 mV, respectively, using a combination of redox buffers, protein-protein equilibrium and thermodynamic linkage. In addition, a nonactive site disulfide was identified between Cys28 and Cys.113 in hGrx2 using redox buffers and chemical digestion. This disulfide confers nearly five kcal mol-1 additional stability by linking the C-terminal helix to the bulk of the protein. The redox potential of this nonactive site disulfide was determined to be -317 mVand is thus expected to be present in all but the most reducing conditions in vivo. As all human glutaredoxins contain additional nonactive site cysteine residues, a full phylogenetic analysis was performed to help elucidate their structural and functional roles. Three distinct groups were found: Grx1, Grx2, and Grx5, the latter representing a highly conserved group of monothiol glutaredoxins having a C-G-F-S active site sequence, with clear homologs from bacteria to human. Grx1 and Grx2 diverged from a common ancestor before the origin vertebrates, possibly even earlier in animal evolution. The highly stabilizing nonactive site disulfide observed in hGrx2 is found to be a conserved feature within the deuterostomes and appears to be the only additional conserved intramolecular disulfide within the glutaredoxins.
Place, publisher, year, edition, pages
2007. Vol. 68, no 4, 879-892 p.
Biochemistry and Molecular Biology Biophysics
IdentifiersURN: urn:nbn:se:sh:diva-14208DOI: 10.1002/prot.21416ISI: 000249188900008PubMedID: 17546662ScopusID: 2-s2.0-34548836048OAI: oai:DiVA.org:sh-14208DiVA: diva2:467956