Category:TP5

Sesquiterpene (C15)

Ring configuration

Germacrane

Sesquiterpenes

Biosynthesis

Overview

The starting point is squalene, which is formed by joining two FPPs tail-to-tail. Bacterial cyclases use squalene directly^[1], but those of the other species use 2,3-oxidosqualene for cyclization.

squalene	2,3-oxidosqualene

• In bacteria, squalene is cyclized via the 17α-deoxydammarenyl cation to hopene and other triterpenes.
• In eukaryotes, 2,3-oxidosqualene is cyclized via the protosteryl cation to lanosterol (animals and fungi), cycloartenol (plants) or parkeol (sea cucumbers) by a series of 1,2-hydride and methyl shifts (Wagner-Meerwein shifts).
• In plants, a trace amount of phytosterols comes from lanosterol ^[2] At3g45130 is lanosterol synthase in Arabidopsis and its orthologs exist in asterids Taraxacum officinale and Panax ginseng and eurosid Luffa cylindrica. Lanosterol synthase exists broadly among eudicots ^[3]. Parkeol is also widespread in plants.
• In plants, various triterpenes arise from the 17β-dammarenyl cation.

References

1. ↑ Bacterial squalene cyclases can accept oxidosqualene as their substrates, but oxidosqualene usually does not exist in bacteria
2. ↑ Ohyama K, Suzuki M, Kikuchi J, Saito K, Muranaka T (2009) Dual biosynthetic pathways to phytosterol via cycloartenol and lanosterol in Arabidopsis Proc Natl Acad Sci USA 106(3):725-730
3. ↑ Kolesnikova MD, Xiong Q, Lodeiro S, Hua L, Matsuda SPT (2006) Lanosterol biosynthesis in plants Arch Biochem Biophys 447:87-95

Sesquiterpene Synthase

farnesyl diphosphate
farnesyl cation
	farnesane, acyclic ones
	cyclobutane, cyclopentane
	cyclofarnesane
	germacrane (elemane, 12-6/12-8 germacranolide, furano- nor- homo- seco-germacrane, bicyclogermacrane, lepidozane) [1] eudesmane (emmotin, oppositane, farfugin, cycloeudesmane, gorgonane, valerane/Jatamansane, spirovetivane (= vetispirane), copaane, others) eremophilane (furano-, seco-, abeo-, nor-, chiloscyphane, aristolane, nardosinane, brasilane (?), cacalol, page 133 fukinane Petasites japonicus, ishwarane
	humulane (caryyllophyllane, bicyclohumulane, africanane)
nerolidyl cation
	bisabolane cuparane (herbertane liverwort,fungi, laurane Laurencia spp. (marine), cyclolaurane, trichothecane (from scirpane), gymnomitrane)
	cycloheptenyl cation
	cadinane (nor, seco, bulgarane,calamenene, muurolane, amorphane, alliacane/primnatriene, oplopane, mutisianthol)
	drimane (iresin, seco, coloratane)
	guaiane (guaianolide, dimer, seco, abeo, xanthane, carabrane, pseudoguaiane, cubebane, ivaxillarane, valerenane) cycloguaiane (aromadendrane, patchoulane, rotundane, bourbonane)
	himachalane (lippifoliane, longipinane, longibornane, longifolane)
	daucane (isodaucane)
	(proto)illudane (illudane, sterpurane, illudalane, isolactarane, merulane, lactarane, marasmane)
	furodysin (furodysinin)
	chamigrane (secochamigrane)
	acorane
	Others pinguisane, picrotoxane, perforane, pacifigorgiane, asteriscane, botrydial Tricyclic Cedrane (isocedrane) Prezizaane (zizaane)