Heterologous expression and characterization of a borneol dehydrogenase from Arabidopsis lyrate and its application for the enzymatic resolution of rac-camphor

Arabidopsis has attracted increasing attention to biotechnology as a model plant. Among, many of studies have focused on monoterpenoids metabolism. Borneol is a typical representative of monoterpenoids and widely applied in fragrances and pharmaceuticals. And (+)-camphor also is also attracting more and more interest in the field of pharmaceutical. However, the enzyme involved the conversion of borneol and camphor in Arabidopsis is still unknown. In this study, a borneol dehydrogenase (BDH) from Arabidopsis lyrate was overexpressed in Escherichia coli BL21 (DE3). The optimum pH for reduction and oxidation were 7.5 and 9.0, respectively, and the optimum temperature was 45 ?. The specific activity of reduction reaction for (-)-camphor and (+)-camphor were 1.09 and 0.76 U.mg(-1) which were the highest so far. The AlBDH coupled with glucose dehydrogenase (GDH) of coenzyme regeneration could efficiently convert rac-camphor, yielding 4.64 mM rac-borneol within 3.5 h with a conversion of 92.8%. A single point mutation L205F could successfully be used for enzymatic resolution of 2 mM rac-camphor, yielding 95.9% of (+)-camphor with an ee(s) of > 99%. It also could respectively reduce (+)-camphor and (-)-camphor to optically pure (+)-borneol and (+)-isoborneol. The study of the enzymatic properties of AlBDH lay an important foundation for further studies on the conversion of borneol and camphor in Arabidopsis and provide potential industrial application value for the optically pure enantiomers borneol sustainable synthesis in the future.

Automated summary

In this study, a borneol dehydrogenase (BDH) from Arabidopsis lyrate was cloned and overexpressed in Escherichia coli. The enzymatic properties of BDH were investigated, revealing its optimum conditions for reduction and oxidation reactions of borneol and camphor. Additionally, a single point mutation was found to enable enzymatic resolution of camphor to produce optically pure (+)-camphor. These findings lay an important foundation for further exploring the conversion of borneol and camphor in Arabidopsis and provide potential industrial application value for the sustainable synthesis of optically pure borneol enantiomers.