title: In vivo RNA localization of I factor, a non-LTR retrotransposon, requires a cis-acting signal in ORF2 and ORF1 protein.
abstract: According to the current model of non-LTR retrotransposon (NLR) mobilization, co-expression of the RNA transposition intermediate, and the proteins it encodes (ORF1p and ORF2p), is a requisite for the formation of cytoplasmic ribonucleoprotein complexes which contain necessary elements to complete a retrotransposition cycle later in the nucleus. To understand these early processes of NLR mobilization, here we analyzed in vivo the protein and RNA expression patterns of the I factor, a model NLR in Drosophila. We show that ORF1p and I factor RNA, specifically produced during transposition, are co-expressed and tightly co-localize with a specific pattern (Loc+) exclusively in the cytoplasm of germ cells permissive for retrotransposition. Using an ORF2 mutated I factor, we show that ORF2p plays no role in the Loc+ patterning. With deletion derivatives of an I factor we define an RNA localization signal required to display the Loc+ pattern. Finally, by complementation experiments we show that ORF1p is necessary for the efficient localization of I factor RNA. Our data suggest that ORF1p is involved in proper folding and stabilization of I factor RNA for efficient targeting, through Loc+ patterning, to the nuclear neighborhood where downstream steps of the retrotransposition process occur.
authors.affiliation: Institut de Génétique Humaine, C.N.R.S. 141 rue de la Cardonille, 34396 Montpellier, France.
authors.forename: Maria del Carmen
authors.initials: MC
authors.lastname: Seleme
authors.forename: Olivier
authors.initials: O
authors.lastname: Disson
authors.forename: Stéphanie
authors.initials: S
authors.lastname: Robin
authors.forename: Christine
authors.initials: C
authors.lastname: Brun
authors.forename: Danielle
authors.initials: D
authors.lastname: Teninges
authors.forename: Alain
authors.initials: A
authors.lastname: Bucheton
mesh_terms: D000818:Animals; D001483:Base Sequence; D004330:Drosophila / Q000235:genetics*; D029721:Drosophila Proteins / Q000032:analysis / Q000235:genetics* / Q000502:physiology*; D005260:Female; D009154:Mutation; D009865:Oocytes / Q000737:chemistry; D009866:Oogenesis / Q000235:genetics; D010641:Phenotype; D012333:RNA, Messenger / Q000032:analysis* / Q000737:chemistry; D012194:RNA-Directed DNA Polymerase / Q000235:genetics* / Q000502:physiology; D038621:Regulatory Sequences, Ribonucleic Acid; D018626:Retroelements; D017384:Sequence Deletion
chemical_list: D029721:Drosophila Proteins; C117553:I-element-gag protein, Drosophila; C496854:ORF2 protein, Drosophila; D012333:RNA, Messenger; D038621:Regulatory Sequences, Ribonucleic Acid; D018626:Retroelements; D012194:RNA-Directed DNA Polymerase