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.^[1]^[2] Hajihashemi et al., 2013 find that it is involved in the drought stress response and – because it mimics drought stress – paclobutrazol toxicity.^[1]^[2] Both inhbit transcription of steviol glycoside synthesis genes including ent-kaurene synthase.^[1]^[2] This is believed to reduce steviol content in the final plant product.^[1]^[2]

References

^ ^a ^b ^c ^d Zhou, Xuan; Gong, Mengyue; Lv, Xueqin; Liu, Yanfeng; Li, Jianghua; Du, Guocheng; Liu, Long (2021). "Metabolic engineering for the synthesis of steviol glycosides: current status and future prospects". Applied Microbiology and Biotechnology. 105 (13). Springer: 5367–5381. doi:10.1007/s00253-021-11419-3. ISSN 0175-7598.
^ ^a ^b ^c ^d Hajihashemi, Shokoofeh (2021). "Agronomic practices". Steviol Glycosides. Elsevier. pp. 31–56. doi:10.1016/b978-0-12-820060-5.00002-9.

Fall RR, West CA (1971). "Purification and properties of kaurene synthetase from Fusarium moniliforme". J. Biol. Chem. 246 (22): 6913–28. PMID 4331199.
Yamaguchi S, Saito T, Abe H, Yamane H, Murofushi N, Kamiya Y (1996). "Molecular cloning and characterization of a cDNA encoding the gibberellin biosynthetic enzyme ent-kaurene synthase B from pumpkin (Cucurbita maxima L.)". Plant J. 10 (2): 203–13. doi:10.1046/j.1365-313X.1996.10020203.x. PMID 8771778.
Kawaide H, Imai R, Sassa T, Kamiya Y (1997). "Ent-kaurene synthase from the fungus Phaeosphaeria sp. L487. cDNA isolation, characterization, and bacterial expression of a bifunctional diterpene cyclase in fungal gibberellin biosynthesis". J. Biol. Chem. 272 (35): 21706–12. doi:10.1074/jbc.272.35.21706. PMID 9268298.
W, Sassa T; Kawaide, H; Ishizaki, A; Shinoda, S; Otsuka, M; Mitsuhashi, W; Sassa, T (2000). "Cloning of a full-length cDNA encoding ent-kaurene synthase from Gibberella fujikuroi: functional analysis of a bifunctional diterpene cyclase". Biosci. Biotechnol. Biochem. 64 (3): 660–4. doi:10.1271/bbb.64.660. PMID 10803977.

v t e Carbon–oxygen lyases (EC 4.2) (primarily dehydratases)
4.2.1: Hydro-Lyases	Carbonic anhydrase Fumarase Aconitase Enolase Alpha Enolase 2 Enoyl-CoA hydratase/3-Hydroxyacyl ACP dehydrase Methylglutaconyl-CoA hydratase Tryptophan synthase Cystathionine beta synthase Porphobilinogen synthase 3-Isopropylmalate dehydratase Urocanase Uroporphyrinogen III synthase Nitrile hydratase
4.2.2: Acting on polysaccharides	Hyaluronate lyase Pectin lyase
4.2.3: Acting on phosphates	Threonine synthase
4.2.99: Other	Carboxymethyloxysuccinate lyase Hydroperoxide lyase

v t e Enzymes
Activity	Active site Binding site Catalytic triad Oxyanion hole Enzyme promiscuity Diffusion-limited enzyme Cofactor Enzyme catalysis
Regulation	Allosteric regulation Cooperativity Enzyme inhibitor Enzyme activator
Classification	EC number Enzyme superfamily Enzyme family List of enzymes
Kinetics	Enzyme kinetics Eadie–Hofstee diagram Hanes–Woolf plot Lineweaver–Burk plot Michaelis–Menten kinetics
Types	EC1 Oxidoreductases (list) EC2 Transferases (list) EC3 Hydrolases (list) EC4 Lyases (list) EC5 Isomerases (list) EC6 Ligases (list) EC7 Translocases (list)