[P004] Poster

1:00 PM - 1:50 PM JST(4:00 AM - 4:50 AM UTC)

[P02-214] A Recyclable Biocatalyst Platform for Highly Diastereoselective Production of D-β-Hydroxy-α-Amino Acids via Engineered D-Threonine aldolase

○Sung-Hyun Park¹, Kil Koang Kwon^1,2,3, Seung-Goo Lee^1,2,3,4 (1. Synthetic Biology Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon 34141, Republic of Korea (Korea), 2. Korea Biofoundry, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon 34141, Republic of Korea (Korea), 3. Department of Biosystems and Bioengineering, KRIBB School of Biotechnology, University of Science and Technology (UST), Daejeon 34113, Republic of Korea (Korea), 4. Graduate School of Engineering Biology, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Republic of Korea (Korea))

Keywords:

D-β-Hydroxy-α-amino acids,D-Threonine aldolase,Biocatalyst,Stereospecificity,Sustainability

D-β-Hydroxy-α-amino acids are important building blocks for various pharmaceuticals, including antibiotics, anticancer agents, and immunomodulators. However, their asymmetric synthesis remains a significant challenge due to the presence of adjacent chiral centers at the Cα and Cβ positions. In D-Threonine aldolase-catalyzed reactions, diastereoselectivity at the Cβ position is inherently low and progressively decreases over the course of the reaction. In this study, key structural motifs governing Cβ diastereoselectivity were identified for the first time, and the corresponding variants were developed as whole-cell biocatalysts to enable highly stereoselective reactions. In addition, a simple and robust permeabilization and immobilization strategy was established to sustain high catalytic activity over repeated operation. The resulting biocatalyst beads consistently achieved titers exceeding 20 g/L of D-threonine with diastereomeric excess exceeding 97 % per cycle over ten consecutive cycles without activity loss. Moreover, the platform demonstrated potential for producing other D-β-hydroxy-α-amino acids. The combination of rational enzyme engineering and a recyclable biocatalyst platform effectively prevented the time-dependent decline in stereoselectivity and enabled sustained high catalytic performance. These results demonstrate a viable strategy for the asymmetric and sustainable production of D-β-hydroxy-α-amino acids.