Heterodimeric geranyl(geranyl)diphosphate synthase from hop (Humulus lupulus) and the evolution of monoterpene biosynthesis

  • Wang G
  • Dixon R
  • 70

    Readers

    Mendeley users who have this article in their library.
  • 75

    Citations

    Citations of this article.

Abstract

Myrcene, which accounts for 30-50% of the essential oil in hop (Humulus lupulus L.) trichomes, derives from geranyl diphosphate (GPP), the common precursor of monoterpenes. Full-length sequences of heterodimeric GPP synthase small subunit (GPPS.SSU, belonging to the SSU I subfamily) and large subunit (LSU) cDNAs were mined from a hop trichome cDNA library. The SSU was inactive, whereas the LSU produced GPP, farnesyl diphosphate, and geranylgeranyl diphosphate (GGPP) from dimethylallyl diphosphate and isopentenyl diphosphate in vitro. Coexpression of both subunits in Escherichia coli yielded a heterodimeric enzyme exhibiting altered ratios of GPP and GGPP synthase activities and greatly enhanced catalytic efficiency. Transcript analysis suggested that the heterodimeric geranyl(geranyl)diphosphate synthase [G(G)PPS] is involved in myrcene biosynthesis in hop trichomes. The critical role of the conserved CxxxC motif (where "x" can be any hydrophobic amino acid residue) in physical interactions between the 2 subunits was demonstrated by using site-directed mutagenesis, and this motif was used in informatic searches to reveal a previously undescribed SSU subfamily (SSU II) present in both angiosperms and gymnosperms. The evolution and physiological roles of SSUs are discussed.

Get free article suggestions today

Mendeley saves you time finding and organizing research

Sign up here
Already have an account ?Sign in

Find this document

Get full text

Authors

  • G. Wang

  • R. A. Dixon

Cite this document

Choose a citation style from the tabs below

Save time finding and organizing research with Mendeley

Sign up for free