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We report the first X-ray structure of the unique "head-to-middle" monoterpene synthase, lavandulyl diphosphate synthase (LPPS). LPPS catalyzes the condensation of two molecules of dimethylallyl diphosphate (DMAPP) to form lavandulyl diphosphate, a precursor to the fragrance lavandulol. The structure is similar to that of the bacterial cis-prenyl synthase, undecaprenyl diphosphate synthase (UPPS), and contains an allylic site (S1) in which DMAPP ionizes and a second site (S2) which houses the DMAPP nucleophile. Both S-thiolo-dimethylallyl diphosphate and S-thiolo-isopentenyl diphosphate bind intact to S2, but are cleaved to (thio)diphosphate, in S1. His78 (Asn in UPPS) is essential for catalysis and is proposed to facilitate diphosphate release in S1, while the P1 phosphate in S2 abstracts a proton from the lavandulyl carbocation to form the LPP product. The results are of interest since they provide the first structure and structure-based mechanism of this unusual prenyl synthase., (© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Abstract: We report the first X‐ray crystallographic structure of the “head‐to‐middle” prenyltransferase, isosesquilavandulyl diphosphate synthase, involved in biosynthesis of the merochlorin class of antibiotics. The protein adopts the ζ or cis‐prenyl transferase fold but remarkably, unlike tuberculosinol adenosine synthase and other cis‐prenyl transferases (e.g. cis‐farnesyl, decaprenyl, undecaprenyl diphosphate synthases), the large, hydrophobic side chain does not occupy a central hydrophobic tunnel. Instead, it occupies a surface pocket oriented at 90° to the hydrophobic tunnel. Product chain‐length control is achieved by squeezing out the ligand from the conventional allylic S1 binding site, with proton abstraction being achieved using a diphosphate‐Asn‐Ser relay. The structures revise and unify our thinking as to the mechanism of action of many other prenyl transferases and may also be of use in engineering new merochlorin‐class antibiotics. [ABSTRACT FROM AUTHOR]

We report the first X-ray structure of the unique 'head-to-middle' monoterpene synthase, lavandulyl diphosphate synthase (LPPS). LPPS catalyzes the condensation of two molecules of dimethylallyl diphosphate (DMAPP) to form lavandulyl diphosphate, a precursor to the fragrance lavandulol. The structure is similar to that of the bacterial cis-prenyl synthase, undecaprenyl diphosphate synthase (UPPS), and contains an allylic site (S1) in which DMAPP ionizes and a second site (S2) which houses the DMAPP nucleophile. Both S-thiolo-dimethylallyl diphosphate and S-thiolo-isopentenyl diphosphate bind intact to S2, but are cleaved to (thio)diphosphate, in S1. His78 (Asn in UPPS) is essential for catalysis and is proposed to facilitate diphosphate release in S1, while the P1 phosphate in S2 abstracts a proton from the lavandulyl carbocation to form the LPP product. The results are of interest since they provide the first structure and structure-based mechanism of this unusual prenyl synthase. [ABSTRACT FROM AUTHOR]

The article presents a diagram related to the article "Structure and Function of a "Head-to-Middle" Prenyltransferase: Lavandulyl Diphosphate Synthase" by Y. Ma and colleagues in the current issue.

Die irreguläre Terpensynthase Lavandulyldiphosphatsynthase (LPPS) produziert die Vorstufe des kommerziell wichtigen Lavendelduftstoffs Lavandulol durch einen ungewöhnlichen “Kopf ‐ zur ‐ Mitte” ‐ Mechanismus. E. Oldfield, R. ‐ T. Guo, Y. Ma et al. präsentieren in der Zuschrift auf S. 4799 ff. die erste Struktur von LPPS im Komplex mit seinem Substrat. Die schmetterlingsförmige Struktur ähnelt der von Proteinen, die an der Biosynthese bakterieller Zellwände beteiligt sind, und führt zu einem einzigartigen Kondensationsmechanismus, der von allgemeinem Interesse im Kontext der Terpensynthese ist. [ABSTRACT FROM AUTHOR]