title: Sequence, structure and evolution of the ecdysone-inducible Lsp-2 gene of Drosophila melanogaster.
abstract: The Lsp-2 gene encodes a major larval serum protein (hexamerin) of Drosophila melanogaster. Transcription of Lsp-2 is controlled by 20-hydroxyecdysone. Here we report the analysis of the structure of the Lsp-2 gene including the adjacent 5' and 3' sequences. In contrast to all other known hexamerin genes, Lsp-2 does not contain an intron. The Lsp-2 mRNA measures 2312 bases, as deduced from experimental determination of the transcription-start and stop sites and conceptual translation results in a 718 amino acid hexamerin subunit, including a 21-amino-acid signal peptide. While the calculated molecular mass of the native 697-amino-acid subunit is 83.5 kDa, mass spectrometry gave a value of 74.5 kDa. We detected in the Lsp-2 gene a 2052-bp antisense ORF that probably does not code for any protein. An unusual accumulation of rarely used codon triplets was found at the 5' and 3' ends of the Lsp-2 ORF. The calculated secondary structure matches well with that of arthropod hemocyanins. Electron micrographs show for LSP-2 hexamers a cubic shape, which can not be easily reconciled with its hexameric structure. Phylogenetic analysis revealed that LSP-2 diverged from the LSP-1 like hexamerins after separation of the Diptera from other insect orders.
authors.affiliation: Institut Jacques-Monod, Département Biologie du Développement, CNRS, Paris, France.
authors.forename: S
authors.initials: S
authors.lastname: Mousseron-Grall
authors.forename: J
authors.initials: J
authors.lastname: Kejzlarová-Lepesant
authors.forename: T
authors.initials: T
authors.lastname: Burmester
authors.forename: C
authors.initials: C
authors.lastname: Chihara
authors.forename: M
authors.initials: M
authors.lastname: Barray
authors.forename: E
authors.initials: E
authors.lastname: Delain
authors.forename: R
authors.initials: R
authors.lastname: Pictet
authors.forename: J A
authors.initials: JA
authors.lastname: Lepesant
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003062:Codon; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000235:genetics*; D004440:Ecdysone / Q000494:pharmacology*; D004790:Enzyme Induction; D017344:Genes, Insect; D019476:Insect Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D010802:Phylogeny; D016385:TATA Box
chemical_list: D003062:Codon; D029721:Drosophila Proteins; D019476:Insect Proteins; C034648:larval serum protein, Drosophila; D004440:Ecdysone