Crystal structure of a multifunctional 2-Cys peroxiredoxin heme-binding protein 23 kDa/proliferation-associated gene product

Abstract

Heme-binding protein 23 kDa (HBP23), a rat isoform of human proliferation-associated gene product (PAG), is a member of the peroxiredoxin family of peroxidases, having two conserved cysteine residues. Recent biochemical studies have shown that HBP23/ PAG is an oxidative stress-induced and proliferation-coupled multifunctional protein that exhibits specific bindings to c-Abl protein tyrosine kinase and heme, as well as a peroxidase activity. A 2.6-Å resolution crystal structure of rat HBP23 in oxidized form revealed an unusual dimer structure in which the active residue Cys-52 forms a disulfide bond with conserved Cys-173 from another subunit by C-terminal tail swapping. The active site is largely hydrophobic with partially exposed Cys-173, suggesting a reduction mechanism of oxidized HBP23 by thioredoxin. Thus, the unusual cysteine disulfide bond is involved in peroxidation catalysis by using thioredoxin as the source of reducing equivalents. The structure also provides a clue to possible interaction surfaces for c-Abl and heme. Several significant structural differences have been found from a 1-Cys peroxiredoxin, ORF6, which lacks the C-terminal conserved cysteine corresponding to Cys-173 of HBP23.

Redox-based regulation of signal transduction: Principles, pitfalls, and promises

“…Originally these enzymes were thought to be relatively weak scavengers of H 2 O 2 , but recent work shows that are as active as peroxidases as either catalase or glutathione peroxidase. What distinguishes peroxiredoxins from other peroxidases is their interaction with numerous regulatory proteins, including c-Abl, c-Myc, JNK, and the PDGF receptor [62,[68][69][70][71]. Little is known about how the oxidation state of Prxs influences protein-protein interactions, but one intriguing possibility is that oxidation state of peroxiredoxins may influence the subcellular location or activity of interacting factors.…”

A mosquito 2-Cys peroxiredoxin protects against nitrosative and oxidative stresses associated with malaria parasite infection

“…NIH-PA Author Manuscript NIH-PA Author Manuscript superfamily [7,8]. Unlike most peroxidases-which contain a heme ring at their active site (e.g., cytochrome c peroxidase) or a redox-sensitive moiety like selenocysteine (glutathione peroxidase; GPx), vanadium (algal bromoperoxide), or flavin (bacterial NADH peroxidase)-Prxs lack cofactor metal ions, prosthetic groups, or cofactors [9].…”

“…A 2-Cys Prx initially reacts with hydroperoxides at the N-terminal Cys (-SH), thus oxidizing the residue to sulfenic acid (-SOH). This cysteinyl-sulfenic acid is unstable and attacks the C-terminal Cys of a second subunit forming an intermolecular disulfide bridge (-SS-) [8]; thus there are two disulfides in a head-to-tail dimer. To regenerate the active 2-Cys Prx, the disulfide must be reduced.…”

Peroxiredoxin 1 – an antioxidant enzyme in cancer

“…Peroxiredoxins (PRDXs), a family of this kind of antioxidants, are classified on the basis of having either one (1‐Cys) or two (2‐Cys) conserved cysteine residues 5. PRDX1 is a member of the 2‐Cys PRDXs subfamily and is present mainly in the cytosol 6. PRDX1 containing a cysteine at the N‐terminal Cys 52 detoxifies peroxides at the expense of Cys 52 oxidation through intermolecular disulphide formation with the other conserved C‐terminal Cys 173 residue 7.…”