8.A.147.  The Peroxiredoxin Heme-binding Protein, Tpx1 (Tpx1) Family

Tpx1 is a peroxiredoxin that binds hemin and regulates the heme-iron/siderophore-iron transporter 3, Str3 (TC# 2.A.1.16.9). Tpx1 (Q74887; 192 aas and 0 - 2 possible TMSs), is a high affinity binding partner of Str3 (Normant et al. 2020). Under microaerobic conditions, cells deficient in heme biosynthesis and lacking the heme receptor Shu1 exhibit poor hemin-dependent growth in the absence of Tpx1, a cytoplasmic heme binding protein. Tpx1 exhibits an equilibrium constant value of 0.26 muM for hemin. The association of Tpx1 with hemin protects hemin from degradation by H2O2, and the peroxidase activity of hemin is lowered when it is bound to Tpx1 (Normant et al. 2020).


 

References:

Chen, J.W., C. Dodia, S.I. Feinstein, M.K. Jain, and A.B. Fisher. (2000). 1-Cys peroxiredoxin, a bifunctional enzyme with glutathione peroxidase and phospholipase A2 activities. J. Biol. Chem. 275: 28421-28427.

Normant, V., A. Brault, M. Avino, T. Mourer, T. Vahsen, J. Beaudoin, and S. Labbé. (2020). Hemeprotein Tpx1 interacts with cell-surface heme transporter Str3 in Schizosaccharomyces pombe. Mol. Microbiol. [Epub: Ahead of Print]

Sharapov, M.G., R.G. Goncharov, S.B. Parfenyuk, O.V. Glushkova, and V.I. Novoselov. (2022). The Role of Phospholipase Activity of Peroxiredoxin 6 in Its Transmembrane Transport and Protective Properties. Int J Mol Sci 23:.

Examples:

TC#NameOrganismal TypeExample
8.A.147.1.1

Tpx1 is a peroxiredoxin that binds hemin and regulates the heme-iron/siderophore-iron transporter 3, Str3 (TC# 2.A.1.16.9). Tpx1 (Q74887; 192 aas and 0 - 2 possible TMSs), is a high affinity binding partner of Str3 (Normant et al. 2020).

Str3 of Schizosaccharomyces pombe (Fission yeast)

 
8.A.147.1.2

Peroxiredoxin of 180 aas and 0 - 2 TMSs.

Peroxiredoxin of Bacillus subtilis

 
8.A.147.1.3

Peroxiredoxin 6 (Prdx6), of 224 aas and 0 TMSs, is a multifunctional eukaryotic antioxidant enzyme. Mammalian Prdx6 possesses peroxidase activity against a wide range of organic and inorganic hydroperoxides as well as phospholipase A2 (aiPLA2) activity, which plays an important role in the reduction of oxidized phospholipids and cell membrane remodeling (Chen et al. 2000). Exogenous Prdx6 is able to penetrate inside the cell via its phospholipase activity (Sharapov et al. 2022).

Prdx6 of Homo sapiens