Sir2 family proteins regulate terpenoid synthesis by deacetylation of 3-hydroxy-3-methylglutaryl-CoA synthase

Abstract Terpenoids are the main components of plant essential oils, and each stage of their synthesis pathway has been identified. However, there are few reports on the regulatory mechanism of this synthesis pathway. Our previous research showed that increasing the gene expression level of one of the key rate-limiting enzymes in the pathway, 3-hydroxy-3-methylglutaryl-CoA synthase (HMGS), can promote this synthesis pathway. In this study, we cloned Sir2 deacetylase family genes in the essential oil-producing plant Litsea cubeba, analysed their functions, and found that overexpression of this gene family can also effectively increase the type and production of terpenoids. In addition, overexpression of this gene family induced phenotypes such as excessive growth and enlarged vegetative organs in plants. Subsequently, we analysed the regulatory mechanism of the Sir2 family and found that these proteins can increase the enzymatic activity of HMGS through deacetylation, thereby promoting the synthesis of terpenoids as the final product. This study discovered a posttranslational regulatory mechanism in the terpenoid synthesis pathway. In addition, this study also provides an effective metabolic engineering method to increase the yield of plant terpenoids while increasing the biomass of plants.