Sequence-specific single-strand RNA binding protein encoded by the human LINE-1 retrotransposon

Abstract

several kinds of tumor cells (Leibold et al., 1990; Institutes of Health, Bethesda, MD 20892 and 2 Carnegie Institution of Bratthauer and Fanning, 1992). ORF2 predicts an Washington, 1530 P Street NW, Washington, DC 20005, USA~1 49 kDa protein with which are associated two activities, 3 Corresponding author DNA endonuclease (Feng et al., 1996) and reverse transcriptase (Dombroski et al., 1991; Mathias et al., 1991; Previous experiments using human teratocarcinoma Moran et al., 1996; Sassaman et al., 1997 et al., 1996). L1Hs RNA(s), the p40 RNP complex. We have nowPreviously we showed that p40 occurs in a cytoplasmic investigated the interaction between partially purified ribonucleoprotein complex (called the p40 RNP complex) p40 and L1Hs RNA in vitro using an RNA binding in human teratocarcinoma cells growing in culture (Hohjoh assay dependent on co-immunoprecipitation of p40 and and Singer, 1996). This p40 RNP complex contains L1Hs bound RNA. These experiments identified two p40RNA and the RNA appears to be directly bound to p40. binding sites on the full-length sense strand L1HsThe p40 RNP complex is large; it elutes in the void RNA. Both sites are in the second ORF of the 6000 nt volume of a Sephacryl S-400 column and is thus likely RNA: site A between residues 1999 and 2039 and site to be Ͼ700 kDa. When the p40 RNP complex is treated B between residues 4839 and 4875. The two RNA with high salt, the RNA is released and p40 can be segments share homologous regions. Experiments recovered as multimers in the size range 200 kDa; treatinvolving UV cross-linking followed by immunoment of the p40 RNP complex with various ribonucleases precipitation indicate that p40 in the in vitro complex yields similar multimers (Hohjoh and Singer, 1997). No is directly associated with L1Hs RNA, as it is in the components of the complexes other than L1Hs RNA p40 RNP complex found in teratocarcinoma cells. Results Preparation of p40

Trex‐1 deficiency in rheumatoid arthritis synovial fibroblasts

“…The observation that RNA interference against L1-ORF1p induces morphologic differentiation, reduces proliferation, and decreases the expression of some genes (8,9) suggests that L1-ORF1p might have features of a transcription factor. ORF1p has been reported to be an RNA binding protein (10), and more recent evidence is in accordance with the hypothesis that L1-ORF1p also binds ssDNA (11,12).…”

Non-LTR retrotransposons encode noncanonical RRM domains in their first open reading frame

“…It corresponds to the 3Ј-terminal nucleotides of a longer 41-mer that specifically copurifies with endogenous human L1ORF1p (12). In size exclusion chromatography 27L1 RNA is delayed with respect to 27U RNA, indicating that it folds into a more compact stem-loop structure.…”

“…It binds single-stranded RNA and DNA with high affinity (12,13) and is essential for retrotransposition of L1 (14). Like ORF2p, it shows a remarkable cis preference, that is, it associates preferentially with its encoding transcript (15,16).…”

Ataxia telangiectasia mutated (ATM) modulates long interspersed element-1 (L1) retrotransposition in human neural stem cells

“…RC-L1s are 6 kb in length and contain two ORFs that encode proteins required for their mobility (5). ORF1 encodes a protein (ORF1p) with RNA binding and nucleic acid chaperone activity (6,7), whereas ORF2 encodes a protein (ORF2p) with endonuclease (8) and reverse transcriptase (9) activities. L1 retrotransposition occasionally can lead to disease and can impact human genome structural variation by various mechanisms (1,10,11).…”