Interfacial Engineering Circumvents Activity–Stability Trade-Off in <scp>L</scp> -Threonine Aldolase for High-Yield <scp>L</scp> - <i>threo</i> -MTPS

L-Threonine aldolase (LTA) is pivotal for β-hydroxy-α-amino acids (β-HAAs) synthesis but is limited by poor thermostability and activity-stability trade-off. Here, we applied interfacial engineering to <i>Faecalimicrobium dakarense</i> LTA, targeting nonconserved residues at subunit interfaces. The resulting variant M3 (L17F/V129R/L206W) exhibited 1.23-fold higher specific activity and significantly enhanced thermostability (<i>T</i>₅₀⁶⁰ + 20.5 °C; <i>T</i>_m + 13.1 °C). In a 1 L system, M3 produced the agrochemical precursor L-<i>threo</i>-4-methylsulfonyl-phenylserine in 2.49-fold higher yield than wild-type. Scaling up to 10 L, M3 achieved 95.7% conversion and 84.9% diastereomeric excess (<i>de</i>), with a high space-time yield of 10.5 g·L^-1·h^-1. Molecular simulations revealed tighter subunit packing, expanded hydrogen-bonding networks, and enhanced rigidity, collectively improving tetramer stability and catalytic performance. This work presents a generalizable interfacial engineering strategy to decouple activity-stability trade-offs in multimeric enzymes, advancing industrial β-HAAs synthesis.