Engineering of chloroflexus islandicus amylosucrase enables efficient whole-cell biocatalysis for α-arbutin production

Abstract

α-Arbutin is a skin-whitening compound widely used in cosmetic and skincare products due to its superior tyrosinase inhibitory activity and improved safety profile compared with hydroquinone. Although the use of amylosucrase for the enzymatic glycosylation of hydroquinone into α-arbutin represents an effective approach for α-arbutin production, the process remains limited by hydroquinone oxidation, low catalytic efficiency, and the requirement for antioxidant supplementation. In this study, a structure-guided protein engineering strategy was employed to improve the performance of amylosucrase from Chloroflexus islandicus (CiAS) for α-arbutin biosynthesis. Eleven CiAS variants were designed based on oxidation-prone surface residues and computational stability predictions and subsequently expressed in Escherichia coli. Among the engineered variants, CiAS-M250A exhibited the highest catalytic performance under the tested whole-cell biocatalytic conditions, reaching 250.2% relative activity compared with the E. coli expressing the CiAS wild-type enzyme. Furthermore, process optimization using the E. coli CiAS-M250A whole-cell biocatalyst resulted in α-arbutin production of 1.1 g/L, corresponding to a molar yield of 40%, without the addition of ascorbic acid. These results demonstrate that structure-guided engineering of amylosucrase is an effective strategy for developing robust and economically attractive whole-cell biocatalysts for sustainable α-arbutin production.

Keywords

Whole-cell biocatalyst / Amylosucrase / Alpha-arbutin / Enzyme engineering / Computational protein design

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Funding

TGIST Internship by the National Science and Technology Development Agency (NSTDA).(SCA-CO-2568-23974-TH)

the National Science, Research and Innovation Fund, Thailand Science Research and innovation (TSRI)(Grant No.: FFB680075/0337)

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