Limonene synthase

Colby S. M., Alonso W. R., Katahira E. J., McGarvey D. J. and Croteau R. (1993) 4S-limonene synthase from the oil glands of spearmint (Mentha spicata). J. Biol. Chem. 268, 23016-23024. 

SCHWAB, W., WILLIAMS, D. C DAVIS, E. M., CROTEAU, R Mechanism of monoterpene cyclization Stereochemical aspects of the transformation of noncyclizable substrate analogs by recombinant (-)-limonene synthase, (+)-bomyl diphosphate synthase, and (-)-pinene synthase, Arch. Biochem. Biophys., 2001, 392, 123-136. 

WILLIAMS, D. C., MCGARVEY, D. J., KATAHIRA, E. J., CROTEAU, R. Truncation of limonene synthase preprotein provides a fully active pseudomature ... 

BOHLMANN, J., STEELE, C. L., CROTEAU, R. Monoterpene synthases from grand fir (Abies grandis) - cDNA isolation, characterization, and functional expression of myreene synthase, (-X4S)-limonene synthase, and (->-<1 S,5S)- pinene synthase, J. Biol. Chem., 1997, 272, 21784-21792. 

Rajaonarivony, J.I.M., Gershenzon, J. and Croteau, R. (1992) Characterization and mechanism of (4S)-limonene synthase, a monoterpene cyclase from the glandular trichomes of peppermint (Mentha x piperita). Arch. Biochem. Biophys., 296, 49-57. 

Yuba, A., Yazaki, K., Tabata, M., Honda, G. and Croteau, R. (1996) cDNA cloning, characterization, and functional expression of 4S-(-)-limonene synthase from Perilla frutescens. Arch. Biochem. Biophys., 332, 280-7. 

Figure 3 Pathway of (-)-menthol biosynthesis in Mentha. LS, (-)-limonene synthase L30H, (-)-limonene-3-hydroxylase iPD, (-)-frans-isopiperitenol dehydrogenase iPR, (-)-isopiperitenone reductase iPI, ( + )-c/s-isopulegone isomerase PR, ( + )-pulegone reductase MR, (-)-menthone reductase.

Hyatt DC, Youn B, Zhao Y, Santhamma B, Coates RM, Croteau RB, Kang C. Structure of limonene synthase, a simple model for terpenoid cyclase catalysis. Proc. Natl. Acad. Sci. U.S.A. 2007 104 5360-5365. 

The biosynthetic route to menthol, starts from isopentenyl- and dimethylallyl diphosphate, which in the case of mint derive from the triose-pyruvate pathway, and consists of eight discrete steps (see also section 7.1.2). This route was established by feeding experiments with radio-lahelled intermediates and cell-free enzyme studies. [110] Condensation of isopentenyl- and dimethylallyl diphosphate gives geranyl diphosphate, which is cyclised to (-)-limonene. Both steps are Mg +-dependent. By-products of the cyclisation are around 2 % of myrcene and both, a- and y -pinene. The limonene synthases in Mentha piperita and Mentha spicata are identical, which shows how closely related to each other the species are. 

Interest in limonene synthase stems in part from the fact that (-)-limonene is the common precursor of menthol and carvone, respectively, of the essential oils of peppermint and spearmint species (Scheme 6) [79]. The cyclization leading to limonene is the simplest of all terpenoid cyclizations and the reaction has ample precedent in solvolytic model studies [58, 59, 80]. Thus, it is not... 

Consistent with the plastidial location of monoterpene biosynthesis [8], immunocy to chemical studies with limonene synthase confirmed the localization of this enzyme to the leucoplasts of peppermint oil glands [87]. Plastid targeting requires the translation of a preprotein bearing an N-terminal transit peptide that directs the newly synthesized enzyme to the plastid for proteolytic processing to the mature form [88]. The limonene synthase cDNA encodes such a preprotein, with an N-terminal sequence that exhibits the typical properties of a transit peptide (rich in serine and threonine (25-30%), rich in small hydrophobic amino acids with few acidic residues, and a propensity to form amphiphilic helices [89,90]). A precise cleavage site between the transit peptide and mature protein is not obvious in the limonene synthase preprotein, and mass spectral... 

The nearly complete catalytic intolerance for glutamyl and alanyl substitutions in the DDxxD motif of limonene synthase is novel and unlike the much less pronounced effects of comparable substitutions in the sesquiterpene cyclase trichodiene synthase [97, 98]. However, pre-steady state kinetic analysis of trichodiene synthase [101] and several other sesquiterpene synthases [102] has recently shown that product release is rate limiting in these cases, and thus can mask the kinetic influence of the aspartate mutations on earlier steps in the catalytic cycle. In the instance of monoterpene cyclase catalysis, product release is not the slow step since comparison of k at values with GPP and LPP as substrate clearly reveals the initial ionization-isomerization to be rate limiting. Thus, perturbations that influence the first ionization step will be fully reflected in overall rate suppression for limonene synthase. This kinetic sensitivity at the initial steps of the reaction cycle does not, however, explain the near complete intolerance of limonene synthase to aspartate substitution in the DDxxD motif and it is thus tempting to speculate a more specific, but presently unidentified, influence on the requisite isomerization of GPP. 

Scheme 11.45. Some of the monoterpene rearrangement products for which some specific synthases have been found [e.g., (-)-en

Ohara K, Matsunaga E, Nanto K, Yamamoto K, Sasaki K, Ebinuma H, Yazaki K (2010) monoterpene engineering in a woody plant Eucalyptus camaldulensis using a limonene synthase cDNA. Plant Biotech J 8 28-37. doi 10.1111/j.l467-7652.2009.00461.x... 

The sequence of reactions catalyzed by the type A limonene synthase (monoterpene cyclase) (Fig. 4) is initiated by ionization-isomerization... 

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