Structural highlights
Function
[MIBS_STRCO] Catalyzes the cyclization of 2-methylgeranyl diphosphate (2-MeGPP) to 2-methylisoborneol (2-MIB), which likely involves the intermediacy of 2-methyllinalyl diphosphate. Is also able to catalyze the cyclization of geranyl diphosphate (GPP), albeit with much lower efficiency, leading to the formation of a complex mixture of cyclic monoterpenes, consisting of alpha-pinene (6%), beta-pinene (23%), limonene (32%), gamma-terpinene (29%), and delta-terpinene (10%).
Publication Abstract from PubMed
The crystal structure of 2-methylisoborneol synthase (MIBS) from Streptomyces coelicolor A3(2) has been determined in complex with substrate analogues geranyl-S-thiolodiphosphate and 2-fluorogeranyl diphosphate at 1.80 and 1.95 A resolution, respectively. This terpenoid cyclase catalyzes the cyclization of the naturally occurring, noncanonical C-methylated isoprenoid substrate, 2-methylgeranyl diphosphate, to form the bicyclic product 2-methylisoborneol, a volatile C(11) homoterpene alcohol with an earthy, musty odor. While MIBS adopts the tertiary structure of a class I terpenoid cyclase, its dimeric quaternary structure differs from that previously observed in dimeric terpenoid cyclases from plants and fungi. The quaternary structure of MIBS is nonetheless similar in some respects to that of dimeric farnesyl diphosphate synthase, which is not a cyclase. The structures of MIBS complexed with substrate analogues provide insights regarding differences in the catalytic mechanism of MIBS and the mechanisms of (+)-bornyl diphosphate synthase and endo-fenchol synthase, plant cyclases that convert geranyl diphosphate into products with closely related bicyclic bornyl skeletons, but distinct structures and stereochemistries.
Structure of 2-Methylisoborneol Synthase from Streptomyces coelicolor and Implications for the Cyclization of a Noncanonical C-Methylated Monoterpenoid Substrate.,Koksal M, Chou WK, Cane DE, Christianson DW Biochemistry. 2012 Apr 10;51(14):3011-20. Epub 2012 Mar 28. PMID:22455514[1]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Koksal M, Chou WK, Cane DE, Christianson DW. Structure of 2-Methylisoborneol Synthase from Streptomyces coelicolor and Implications for the Cyclization of a Noncanonical C-Methylated Monoterpenoid Substrate. Biochemistry. 2012 Apr 10;51(14):3011-20. Epub 2012 Mar 28. PMID:22455514 doi:10.1021/bi201827a
