Ent-kaurene synthase

The enzyme ent-kaurene synthase (EC 4.2.3.19) catalyzes the chemical reaction


 * ent-copalyl diphosphate $$\rightleftharpoons$$ ent-kaurene + diphosphate

This enzyme belongs to the family of lyases, specifically those carbon-oxygen lyases acting on phosphates. The systematic name of this enzyme class is ent-copalyl-diphosphate diphosphate-lyase (cyclizing, ent-kaurene-forming). Other names in common use include ent-kaurene synthase B, ent-kaurene synthetase B, ent-copalyl-diphosphate diphosphate-lyase, and (cyclizing). This enzyme participates in diterpenoid biosynthesis.

In Stevia
In Stevia spp., ent-kaurene synthase is a required part of the biosynthesis of steviol. Hajihashemi et al., 2013 find that it is involved in the drought stress response and – because it mimics drought stress paclobutrazol toxicity. Both inhbit transcription of steviol glycoside synthesis genes including ent-kaurene synthase. This is believed to reduce steviol content in the final plant product.