Reaction: mycoredoxin + ROOH = mycoredoxin disulfide + H2O + ROH
For diagram of reaction, click here and for mechanism, click here
Other name(s): ahpE (gene name)
Systematic name: mycoredoxin:hydroperoxide oxidoreductase
Comments: Peroxiredoxins (Prxs) are a ubiquitous family of antioxidant proteins. They can be divided into three classes: typical 2-Cys, atypical 2-Cys and 1-Cys peroxiredoxins [1]. The peroxidase reaction comprises two steps centred around a redox-active cysteine called the peroxidatic cysteine. All three peroxiredoxin classes have the first step in common, in which the peroxidatic cysteine attacks the peroxide substrate and is oxidized to S-hydroxycysteine (a sulfenic acid) (see mechanism). The second step of the peroxidase reaction, the regeneration of cysteine from S-hydroxycysteine, distinguishes the three peroxiredoxin classes. For typical 2-Cys Prxs, in the second step, the peroxidatic S-hydroxycysteine from one subunit is attacked by the ‘resolving’ cysteine located in the C-terminus of the second subunit, to form an intersubunit disulfide bond, which is then reduced by one of several cell-specific thiol-containing reductants completing the catalytic cycle. In the atypical 2-Cys Prxs, both the peroxidatic cysteine and its resolving cysteine are in the same polypeptide, so their reaction forms an intrachain disulfide bond. The 1-Cys Prxs conserve only the peroxidatic cysteine, so its regeneration involves direct interaction with a reductant molecule. Mycoredoxin-dependent enzymes are found in Mycobacteria. Following the reduction of the substrate, the sulfenic acid derivative of the peroxidatic cysteine forms a protein mixed disulfide with the N-terminal cysteine of mycoredoxin, which is then reduced by the C-terminal cysteine of mycoredoxin, restoring the peroxiredoxin to active state and resulting in an intra-protein disulfide in mycoredoxin. The disulfide is eventually reduced by mycothiol.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number:
References:
1. Wood, Z.A., Schröder, E., Harris, J.R. and Poole, L.B. Structure, mechanism and regulation of peroxiredoxins. Trends Biochem. Sci. 28 (2003) 32-40. [PMID: 12517450]
2. Hugo, M., Turell, L., Manta, B., Botti, H., Monteiro, G., Netto, L.E., Alvarez, B., Radi, R. and Trujillo, M. Thiol and sulfenic acid oxidation of AhpE, the one-cysteine peroxiredoxin from Mycobacterium tuberculosis: kinetics, acidity constants, and conformational dynamics. Biochemistry 48 (2009) 9416-9426. [PMID: 19737009]
3. Hugo, M., Van Laer, K., Reyes, A.M., Vertommen, D., Messens, J., Radi, R. and Trujillo, M. Mycothiol/mycoredoxin 1-dependent reduction of the peroxiredoxin AhpE from Mycobacterium tuberculosis. J. Biol. Chem. 289 (2014) 5228-5239. [PMID: 24379404]
4. Kumar, A., Balakrishna, A.M., Nartey, W., Manimekalai, M.SS. and Gruber, G. Redox chemistry of Mycobacterium tuberculosis alkylhydroperoxide reductase E (AhpE): Structural and mechanistic insight into a mycoredoxin-1 independent reductive pathway of AhpE via mycothiol. Free Radic. Biol. Med. 97 (2016) 588-601. [PMID: 27417938]
5. Pedre, B., van Bergen, L.A., Pallo, A., Rosado, L.A., Dufe, V.T., Molle, I.V., Wahni, K., Erdogan, H., Alonso, M., Proft, F.D. and Messens, J. The active site architecture in peroxiredoxins: a case study on Mycobacterium tuberculosis AhpE. Chem. Commun. (Camb.) 52 (2016) 10293-10296. [PMID: 27471753]