Identification of a Cinnamoyl-CoA Reductase Involved in Cinnamaldehyde Biosynthesis from Cinnamomum cassia

Abstract

Abstract A significant accumulation of cinnamaldehyde has been found in the barks of Cinnamomum cassia, which are used in traditional Chinese medicine. Cinnamaldehyde exhibits various pharmacological properties such as anti-inflammatory, analgesic, and stomachic effects. However, further confirmation of the biosynthetic pathway for cinnamaldehyde is needed. In this study, we analyzed 15 transcriptomes from five different tissues to understand the accumulation of active components and identify the genes responsible for cinnamaldehyde biosynthesis. Our transcriptome database contained nearly all genes associated with the cinnamaldehyde pathway, with the majority of them demonstrating high abundance in branch barks and barks. We successfully cloned C. cassia cinnamoyl-CoA reductase (CcCCR1), a key gene in the biosynthesis of cinnamaldehyde, and found that its expression pattern mirrored the cinnamaldehyde content level. The recombinant CcCCR1 protein efficiently converted cinnamoyl-CoA into cinnamaldehyde. Compared to Arabidopsis thaliana cinnamoyl-CoA reductase 1 (AtCCR1), CcCCR1 exhibited approximately 17-fold higher catalytic efficiency (kcat/Km). Molecular docking studies also indicated superior catalytic activity of CcCCR1 compared to AtCCR1, which can be utilized for engineering higher cinnamaldehyde production as previously reported. These findings provide valuable insights for the functional characterization of enzyme-coding genes and hold potential for future engineering of cinnamaldehyde biosynthetic pathways.