Engineering a hybrid chemical-biological system for efficient de novo taurine production via computational enzyme...

Taurine, an important sulfur-containing nonpeptidic amino acid, is widely used in the food, pharmaceutical and feed industries. Microbial fermentation has emerged as a promising sustainable alternative to environmentally-unfriendly chemical synthesis for taurine production, but the development of taurine-producing cell factories remains constrained by inefficient heterologous pathways, suboptimal key enzymes activities and limited precursor supply, resulting in low taurine titers. Here, we established an efficient de novo taurine biosynthetic system in Escherichia coli by integrating pathway engineering, enzyme design and a hybrid chemical-biological system. For constructing an efficient taurine biosynthetic route, the sequence-guided enzyme mining was conducted to identify the superior catalysts of HcCDO and AeCSAD. To overcome the intrinsic catalytic bottleneck of AeCSAD, the computational-assisted protein engineering was implemented by integrating large-scale protein language model-based sequence optimization with physics-based energy calculations, yielding an AeCSAD (T410P/T498W) variant with a 3.19-fold increase in activity. To circumvent the poor solubility and low activity of FMO1-like enzymes, a mild H₂O₂-driven terminal oxidation process was established to rapidly and quantitatively convert hypotaurine to taurine. Concurrently, the multilayered metabolic rewiring strategies were performed to coordinately tune the carbon-metabolism and sulfur-assimilation modules, thereby increasing intracellular cysteine availability and driving higher taurine production. By coupling the optimized pathway with post-fermentation chemical oxidation in a fed-batch process, we achieved a taurine titer of 4.08 g/L, the highest reported to date. Collectively, our results established a mechanistically integrated chemical-biological platform for de novo taurine production and provided a generalizable framework for sustainable manufacturing of sulfonic acid-containing compounds.