In vivo RNA localization of I factor, a non-LTR retrotransposon, requires a cis-acting signal in ORF2 and ORF1 protein

Nucleic Acids Res. 2005 Feb 1;33(2):776-85. doi: 10.1093/nar/gki221. Print 2005.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Base Sequence
  • Drosophila / genetics*
  • Drosophila Proteins / analysis
  • Drosophila Proteins / genetics*
  • Drosophila Proteins / physiology*
  • Female
  • Mutation
  • Oocytes / chemistry
  • Oogenesis / genetics
  • Phenotype
  • RNA, Messenger / analysis*
  • RNA, Messenger / chemistry
  • RNA-Directed DNA Polymerase / genetics*
  • RNA-Directed DNA Polymerase / physiology
  • Regulatory Sequences, Ribonucleic Acid*
  • Retroelements*
  • Sequence Deletion

Substances

  • Drosophila Proteins
  • I-element-gag protein, Drosophila
  • ORF2 protein, Drosophila
  • RNA, Messenger
  • Regulatory Sequences, Ribonucleic Acid
  • Retroelements
  • RNA-Directed DNA Polymerase