title: FB-NOF is a non-autonomous transposable element, expressed in Drosophila melanogaster and present only in the melanogaster group.
abstract: Most foldback elements are defective due to the lack of coding sequences but some are associated with coding sequences and may represent the entire element. This is the case of the NOF sequences found in the FB of Drosophila melanogaster, formerly considered as an autonomous TE and currently proposed as part of the so-called FB-NOF element, the transposon that would be complete and fully functional. NOF is always associated with FB and never seen apart from the FB inverted repeats (IR). This is the reason why the FB-NOF composite element can be considered the complete element. At least one of its ORFs encodes a protein that has always been considered its transposase, but no detailed studies have been carried out to verify this. In this work we test the hypothesis that FB-NOF is an active transposon nowadays. We search for its expression product, obtaining its cDNA, and propose the ORF and the sequence of its potential protein. We found that the NOF protein is not a transposase as it lacks any of the motifs of known transposases and also shows structural homology with hydrolases, therefore FB-NOF cannot belong to the superfamily MuDR/foldback, as up to now it has been classified, and can be considered as a non-autonomous transposable element. The alignment with the published genomes of 12 Drosophila species shows that NOF presence is restricted only to the 6 Drosophila species belonging to the melanogaster group.
authors.affiliation: Grup de Mutagènesi, Departament de Genètica i de Microbiologia, Facultat de Biociències, Edifici C, Universitat Autònoma de Barcelona, 08193 Bellaterra (Cerdanyola del Vallès), Spain.
authors.forename: Martí
authors.initials: M
authors.lastname: Badal
authors.forename: Noel
authors.initials: N
authors.lastname: Xamena
authors.forename: Oriol
authors.initials: O
authors.lastname: Cabré
mesh_terms: D000818:Animals; D004251:DNA Transposable Elements; D004331:Drosophila melanogaster / Q000145:classification / Q000235:genetics*; D015870:Gene Expression; D016366:Open Reading Frames; D010802:Phylogeny; D013045:Species Specificity
chemical_list: D004251:DNA Transposable Elements
keywords: C-terminal; CDS; Drosophila melanogaster; EST; FB; FB-NOF expression; IR; Kb; Melanogaster group; NOF function; NOF protein; ORF; PCR; RT-PCR; TE; TPase; Transposable element; UTR; ZF; aa; amino acid; base pair; bp; carboxy terminal; coding sequence; expressed sequence tag; foldback; inverted repeats; kilobase; open reading frame; polymerase chain reaction; reverse transcription-polymerase chain reaction; transposable element; transposase; untranslated region; zinc finger motif