title: The P450 enzyme Shade mediates the hydroxylation of ecdysone to 20-hydroxyecdysone in the Colorado potato beetle, Leptinotarsa decemlineata.
abstract: Ecdysone 20-monooxygenase (E20MO), a cytochrome P450 monooxygenase (CYP314A1), catalyses the conversion of ecdysone (E) to 20-hydroxyecdysone (20E). We report here the cloning and characterization of the Halloween gene Shade (Shd) encoding E20MO in the Colorado potato beetle, Leptinotarsa decemlineata. LdSHD has five conserved motifs typical of insect P450s, ie the Helix-C, Helix-I, Helix-K, PxxFxPE/DRF (PERF) and heme-binding motifs. LdShd was expressed in developing eggs, the first to fourth instars, wandering larvae, pupae and adults, with statistically significant fluctuations. Its mRNA was ubiquitously distributed in the head, thorax and abdomen. The recombinant LdSHD protein expressed in Spodoptera frugiperda 9 (Sf9) cells catalysed the conversion of E to 20E. Dietary introduction of double-stranded RNA (dsRNA) of LdShd into the second instar larvae successfully knocked down the LdShd expression level, decreased the mRNA level of the ecdysone receptor (LdEcR) gene, caused larval lethality, delayed development and affected pupation. Moreover, ingestion of LdShd-dsRNA by the fourth instars also down-regulated LdShd and LdEcR expression, reduced the 20E titre, and negatively influenced pupation. Introduction of 20E and a nonsteroidal ecdysteroid agonist halofenozide into the LdShd-dsRNA-ingested second instars, and of halofenozide into the LdShd-dsRNA-ingested fourth instars almost completely relieved the negative effects on larval performance. Thus, LdSHD functions to regulate metamorphotic processes by converting E to 20E in a coleopteran insect species Le. decemlineata.
authors.affiliation: Education Ministry Key Laboratory of Integrated Management of Crop Diseases and Pests, College of Plant Protection, Nanjing Agricultural University, Nanjing, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Kong
authors.forename: X-P
authors.initials: XP
authors.lastname: Liu
authors.forename: P-J
authors.initials: PJ
authors.lastname: Wan
authors.forename: X-Q
authors.initials: XQ
authors.lastname: Shi
authors.forename: W-C
authors.initials: WC
authors.lastname: Guo
authors.forename: G-Q
authors.initials: GQ
authors.lastname: Li
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001517:Coleoptera / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D004440:Ecdysone / Q000378:metabolism; D004441:Ecdysterone / Q000378:metabolism; D005260:Female; D006900:Hydroxylation; D019476:Insect Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D007814:Larva / Q000378:metabolism; D008297:Male; D008969:Molecular Sequence Data; D010063:Ovum / Q000378:metabolism; D010802:Phylogeny; D011679:Pupa / Q000378:metabolism; D012330:RNA, Double-Stranded / Q000235:genetics / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D011987:Receptors, Steroid / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment
chemical_list: D019476:Insect Proteins; D012330:RNA, Double-Stranded; D011987:Receptors, Steroid; C055469:ecdysone receptor; D004440:Ecdysone; D004441:Ecdysterone; D003577:Cytochrome P-450 Enzyme System
keywords: RNA interference; Shade; ecdysone 20-monooxygenase; ecdysteroidogenesis; performance