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<p>The study of antioxidant enzymes in <i>Avicennia marina</i>, a mangrove species, is crucial because of the plant’s exceptional ability to survive in harsh environments. Catalase (CAT) is particularly important in reducing the damaging effects of reactive oxygen species (ROS), which are generated as a result of various stresses. In the present work, the gene encoding CAT from <i>A. marina</i> (<i>AmCAT</i>) was amplified from the full-length cDNA, cloned into pET32a and expressed as a Thioredoxin (Trx)-tagged fusion protein in <i>E. coli</i>. The recombinant enzyme, which was mainly soluble, exhibited 55,000 U/mg activity after purification. It showed optimal activity at 35&#xa0;°C and pH 7, with high stability up to 40&#xa0;°C and pH 6–8. Trx-AmCAT likely forms a homotetramer with a molecular mass of 280&#xa0;kDa and incorporates four moles of Fe²⁺ per tetramer, essential for its hydrogen peroxide-decomposing activity. The expression and activity of <i>AmCAT</i> in <i>A. marina</i> seedlings were significantly upregulated under stress conditions, particularly in the leaves, indicating its role in stress tolerance. Furthermore, heterologous expression of <i>AmCAT</i> in <i>E. coli</i> enhanced its tolerance to NaCl, H<sub>2</sub>O<sub>2</sub>, butanol, high temperatures, and Pb<sup>2+</sup> (applied as 1 mM Pb(NO<sub>3</sub>)<sub>2</sub> in seedling treatments). These results suggest that <i>AmCAT</i> is a promising candidate, based on its enhanced microbial tolerance for industrial and biochemical applications and also for engineering stress-resistant microorganisms.</p>

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Heterologous expression of a heme-dependent catalase from Avicennia marina confers multi-stress tolerance in Escherichia coli for biotechnological applications

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  • 发表日期：

    2026年4月24日

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  • Azar Shahpiri,
  • Mohammad Rafiei,
  • Seyedeh Maryam Sharafi

摘要

The study of antioxidant enzymes in Avicennia marina, a mangrove species, is crucial because of the plant’s exceptional ability to survive in harsh environments. Catalase (CAT) is particularly important in reducing the damaging effects of reactive oxygen species (ROS), which are generated as a result of various stresses. In the present work, the gene encoding CAT from A. marina (AmCAT) was amplified from the full-length cDNA, cloned into pET32a and expressed as a Thioredoxin (Trx)-tagged fusion protein in E. coli. The recombinant enzyme, which was mainly soluble, exhibited 55,000 U/mg activity after purification. It showed optimal activity at 35 °C and pH 7, with high stability up to 40 °C and pH 6–8. Trx-AmCAT likely forms a homotetramer with a molecular mass of 280 kDa and incorporates four moles of Fe²⁺ per tetramer, essential for its hydrogen peroxide-decomposing activity. The expression and activity of AmCAT in A. marina seedlings were significantly upregulated under stress conditions, particularly in the leaves, indicating its role in stress tolerance. Furthermore, heterologous expression of AmCAT in E. coli enhanced its tolerance to NaCl, H2O2, butanol, high temperatures, and Pb2+ (applied as 1 mM Pb(NO3)2 in seedling treatments). These results suggest that AmCAT is a promising candidate, based on its enhanced microbial tolerance for industrial and biochemical applications and also for engineering stress-resistant microorganisms.