title: Cyclization of all-E- and 2Z-geranylfarnesols by a bacterial triterpene synthase: insight into sesterterpene biosynthesis in Aleuritopteris ferns.
abstract: Aleuritopteris ferns produce triterpenes and sesterterpenes with tricyclic cheilanthane and tetracyclic 18-episcalarane skeletons. The structural and mechanistic similarities between both classes of fern terpene suggest that their biosynthetic enzymes may be closely related. We investigate here whether a triterpene synthase is capable of recognizing geranylfarnesols as a substrate, and is able to convert them to cyclic sesterterpenes. We found that a bacterial triterpene synthase converted all-E-geranylfarnesol (1b) into three scalarane sesterterpenes with 18αH stereochemistry (5, 7 and 8), as well as mono- and tricyclic sesterterpenes (6 and 9). In addition, 2Z-geranylfarnesol (4) was converted into an 18-episcalarane derivative (10), whose skeleton can be found in sesterterpenes isolated from Aleuritopteris ferns. These results provide insight into sesterterpene biosynthesis in Aleuritopteris ferns.
authors.affiliation: Showa Pharmaceutical University.
authors.forename: Junichi
authors.initials: J
authors.lastname: Shinozaki
authors.forename: Masaaki
authors.initials: M
authors.lastname: Shibuya
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Ebizuka
authors.forename: Kazuo
authors.initials: K
authors.lastname: Masuda
mesh_terms: D056450:Alicyclobacillus / Q000201:enzymology* / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D003500:Cyclization; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D029624:Ferns / Q000737:chemistry / Q000201:enzymology*; D005778:Gefarnate / Q000031:analogs & derivatives* / Q000378:metabolism; D008025:Ligases / Q000235:genetics / Q000378:metabolism*; D015394:Molecular Structure; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D054830:Sesterterpenes / Q000378:metabolism*; D013237:Stereoisomerism; D013379:Substrate Specificity; D014315:Triterpenes / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D011994:Recombinant Proteins; D054830:Sesterterpenes; D014315:Triterpenes; D005778:Gefarnate; C043321:geranylfarnesol; D008025:Ligases