Characterization and tissue‐specific expression of two lepidopteran farnesyl diphosphate synthase homologs: Implications for the biosynthesis of ethyl‐substituted juvenile hormones

Abstract

The sesquiterpenoid juvenile hormone (JH) regulates insect development and reproduction. Most insects produce only one chemical form of JH, but the Lepidoptera produce four derivatives featuring ethyl branches. The biogenesis of these JHs requires the synthesis of ethyl-substituted farnesyl diphosphate (FPP) by FPP synthase (FPPS). To determine if there exist more than one lepidopteran FPPS, and whether one FPPS homolog is better adapted for binding the bulkier ethyl-branched substrates/products, we cloned three lepidopteran FPPS cDNAs, two from Choristoneura fumiferana and one from Pseudaletia unipuncta. Amino acid sequence comparisons among these and other eukaryotic FPPSs led to the recognition of two lepidopteran FPPS types. Type-I FPPSs display unique active site substitutions, including several in and near the first aspartate-rich motif, whereas type-II proteins have a more "conventional" catalytic cavity. In a yeast assay, a Drosophila FPPS clone provided full complementation of an FPPS mutation, but lepidopteran FPPS clones of either type yielded only partial complementation, suggesting unusual catalytic features and/or requirements of these enzymes. Although a structural analysis of lepidopteran FPPS active sites suggested that type-I enzymes are better suited than type-II for generating ethyl-substituted products, a quantitative real-time PCR assessment of their relative abundance in insect tissues indicated that type-I expression is ubiquitous whereas that of type-II is essentially confined to the JH-producing glands, where its transcripts are approximately 20 times more abundant than those of type-I. These results suggest that type-II FPPS plays a leading role in lepidopteran JH biosynthesis in spite of its apparently more conventional catalytic cavity.

Frontalin pheromone biosynthesis in the mountain pine beetle, Dendroctonus ponderosae , and the role of isoprenyl diphosphate synthases

“…DponGPPS/FPPS protein was 99% identical to a putative FPPS from Dendroctonus jeffreyi (13) and shared 75%, 70%, 62%, 62%, 50%, and 49% amino acid identity with the FPPSs from A. grandis (11), I. pini (13), Tribolium castaneum (GenBank accession no. XP_972537), P. cochleariae (12), Choristoneura fumiferana (19), and Drosophila melanogaster (GenBank accession no. CAA08919), respectively (Fig.…”

Prophenoloxidases 1 and 2 from the spruce budworm, Choristoneura fumiferana: Molecular cloning and assessment of transcriptional regulation by a polydnavirus

“…3). In the latter, branching order within each cluster did not perfectly match that of recent family-level lepidopteran phylogenies (e.g., LepTree Team, 2007), particularly for PPO1, but such discrepancies are not uncommon for trees constructed using a single gene (see, for example, Cusson et al, 2006). An earlier PPO/ hemocyanin phylogeny (Terwilliger and Ryan 2006) yielded a similar branching pattern, despite very different taxonomic sampling outside the Lepidoptera.…”

Isolation and characterization of farnesyl diphosphate synthase from the cotton boll weevil, Anthonomus grandis

“…Similar N-terminal extensions are found in other insect sequences (Fig. 2, Cusson et al, 2006) and also are observed in plant (Cunillera et al, 1997) and mammalian FPPSs (Martin et al, 2007). The N-terminal extension of AgFPPS displays the characteristics of mitochondrial-targeting peptide and contains RXXS sequence, which is a consensus cleavage motif in mitochondrial targeting peptides (Von Heijne et al, 1989, Fig.…”

“…The female boll weevil produces a sesquiterpene pheromone (Hedin et al, 1979), which is presumably synthesized from FPP. FPPS has been sequenced from several insects including, Agrotis ipsilon (Castillo-Gracia and Couillaud, 1999), Bombyx mori (Kikuchi et al, 2001), Drosophila melanogaster (Sen et al, 2007a), and Choristoneura fumiferana (Cusson et al, 2006).…”