DypB peroxidase for aflatoxin removal: New insights into the toxin degradation process

• Published in: Chemosphere (Oxford) 2024-02, Vol.349, p.140826-140826, Article 140826
• Main Authors: Mangini, V., Rosini, E., Caliandro, R., Mangiatordi, G.F., Delre, P., Sciancalepore, A.G., Pollegioni, L., Haidukowski, M., Mazzorana, M., Sumarah, M.W., Renaud, J.B., Flaig, R., Mulè, G., Belviso, B.D., Loi, M.
• Format: Article
• Language: English
• Subjects: Aflatoxin B1; aflatoxins; Bioremediation; decolorization; Dye decolorizing peroxidase; dyes; feed contamination; Food safety; manganese; Manganese-dependent enzyme; Molecular dynamics; peroxidase; Protein engineering; protein structure; reducing agents
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2023.140826

Aflatoxin B1 (AFB1) is one of the most potent carcinogens and a widespread food and feed contaminant. As for other toxins, many efforts are devoted to find efficient and environmentally-friendly methods to degrade AFB1, such as enzymatic treatments, thus improving the safety of food and feed products. In this regard, the dye decolorizing peroxidase of type B (DypB) can efficiently degrade AFB1. The molecular mechanism, which is required to drive protein optimization in view of the usage of DypB as a mycotoxin reduction agent in large scale application, is unknown. Here, we focused on the role of four DypB residues in the degradation of AFB1 by alanine-scanning (residues 156, 215, 239 and 246), which were identified from biochemical assays to be kinetically relevant for the degradation. As a result of DypB degradation, AFB1 is converted into four products. Interestingly, the relative abundancy of these products depends on the replaced residues. Molecular dynamics simulations were used to investigate the role of these residues in the binding step between protein and manganese, a metal ion which is expected to be involved in the degradation process. We found that the size of the haem pocket as well as conformational changes in the protein structure could play a role in determining the kinetics of AFB1 removal and, consequently, guide the process towards specific degradation products. [Display omitted] •Wild-type decolorizing peroxidase of type B and four variants were investigated.•All enzymes degraded aflatoxin B1 with different efficiency and kinetics.•Four degradation products with different relative abundancies were found.•Mn2+ oxidation to more oxidizing states could promote degradation yield and kinetics.•Protein conformational changes could be required to promote aflatoxin B1 oxidation.