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Enhancing the Substrate Adaptability of Laccase through Ancestral Sequence Reconstruction for Applications in Mycotoxin Detoxification

Summary

Researchers used evolutionary analysis to redesign a fungal enzyme called laccase to better detoxify harmful mold toxins found in grains. The new engineered enzyme (LacANC278) can break down both aflatoxin and zearalenone toxins much more effectively than the original enzyme, and converts them into less harmful substances. This enzyme works without expensive helper chemicals and works well at room temperature, making it practical for treating contaminated corn and other grains.

Background

Mycotoxins such as aflatoxin B1 (AFB1) and zearalenone (ZEN) from moldy grains pose significant health risks to humans and animals. Over 25% of global crops are contaminated with mycotoxins, causing immeasurable economic losses. Enzymatic detoxification offers advantages over traditional physical and chemical methods, with laccases showing promise for converting multiple mycotoxins simultaneously.

Objective

To enhance the substrate adaptability, stability, and catalytic efficiency of laccase LCC5 from Coprinopsis cinerea through ancestral sequence reconstruction for improved mycotoxin detoxification. The study aimed to identify ancestral laccase variants with superior conversion rates for both AFB1 and ZEN.

Results

LacANC278, an ancestral laccase, demonstrated 23% higher conversion rate for AFB1 and 61% higher for ZEN compared to LCC5, with a half-life extended from 4 h to 16 h. Under optimal conditions, LacANC278 achieved 88% and 89% reduction of AFB1 and ZEN respectively in corn powder. The major conversion products were identified as AFQ1 for AFB1 and 2-OH-ZEN for ZEN, both showing significantly reduced toxicity compared to the parent mycotoxins.

Conclusion

Ancestral sequence reconstruction successfully identified LacANC278 as a superior mycotoxin-detoxifying enzyme with broad substrate adaptability and enhanced stability. The enzyme’s ability to efficiently convert multiple mycotoxins without mediators and produce less toxic metabolites demonstrates significant potential for practical application in grain and food safety. This approach provides a novel strategy for enzyme engineering to address multimycotoxin contamination in agricultural products.
  • Published in:Journal of Agricultural and Food Chemistry,
  • Study Type:Experimental Laboratory Study,
  • Source: 10.1021/acs.jafc.5c08713, PMID: 41222013
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