L-cysteine is a naturally occurring sulfur-containing amino acid bearing a reactive thiol group. It plays vital roles in maintaining cellular redox homeostasis and synthesizing bioactive compounds, thus gaining widespread attention and broad applications in: food, pharmaceutical, cosmetic and feed industries. Currently, its industrial production mainly relies on keratin hydrolysis, which causes serious environmental and safety concerns. By contrast, biocatalytic and microbial fermentation have emerged as sustainable and safe alternatives. This review systematically summarizes current bioproduction strategies for L-cysteine, covering biocatalytic pathways and metabolic engineering of microbial cell factories. We further elaborate the metabolic pathways, regulatory networks, and transport systems of L-cysteine in three mainstream microbial chassis, including Escherichia coli, Corynebacterium glutamicum, and Pantoea ananatis. Core production bottlenecks and targeted metabolic engineering solutions are also comprehensively discussed. Finally, future prospects for sustainable industrial L-cysteine production are proposed.
Ming-Li Zhao, Di Wu, Yu-Ting Liao et al.· Critical Reviews in Biotechn...· 0 citations
Zearalenone (ZEN) lactonases are promising biocatalysts for ZEN detoxification, yet the catalytic mechanism underlying ZEN hydrolysis remains poorly understood. Here, we combined structural analysis, quantum-mechanical (QM) calculations, and molecular dynamics (MD) simulations to elucidate the catalytic mechanism and guide enzyme engineering. QM and MD analyses identified a near-attack conformation of the catalytic His245 as essential for proton transfer. Crystal structure analysis revealed that mutations within the active pocket enhanced the local hydrophobic microenvironment, thereby optimizing the reactive conformation through an improved substrate positioning and catalytic residue alignment. Engineering the hydrophobic microenvironment significantly enhanced the activity of ZENM toward multiple substrates. Transfer of the engineered region to another ZEN lactonase, ZHD101, also significantly improved the hydrolytic activity, supporting the potential general applicability of this strategy. Hydrophobic microenvironment engineering might represent a promising strategy for modulating proton transfer and provide a potential framework for improving the activity of ZEN lactonases for food and feed detoxification.
Binbin Ouyang, Zhao Huang, Chenshuo Song et al.· Journal of Agricultural and...· 0 citations
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