Vol 3: Lost in translation: The biogenesis of non-LTR retrotransposon proteins.Report as inadecuate



 Vol 3: Lost in translation: The biogenesis of non-LTR retrotransposon proteins.


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This article is from Mobile Genetic Elements, volume 3.Abstract-Young- APE-type non-LTR retrotransposons non-LTRs typically encode two open reading frames ORFs 1 and 2. The shorter ORF1 translation product ORF1p comprises an RNA binding activity, thought to bind to non-LTR transcript RNA, protect against nuclease degradation and specify nuclear import of the ribonuclear protein complex RNP. ORF2 encodes a multifunctional protein ORF2p comprising apurinic-apyrimidinic endonuclease APE and reverse-transcriptase RT activities, responsible for genome replication and re-integration into chromosomal DNA. However, some clades of APE-type non-LTRs only encode a single ORF—corresponding to the multifunctional ORF2p outlined above and for simplicity referred-to as ORF2 below. The absence of an ORF1 correlates with the acquisition of a 2A oligopeptide translational recoding element some 18–30 amino acids into the N-terminal region of ORF2p. In the case of non-LTRs encoding two ORFs, the presence of ORF1 would necessarily downregulate the translation of ORF2. We argue that in the absence of an ORF1, 2A could provide the corresponding translational downregulation of ORF2. While multiple molecules of ORF1p are required to decorate the non-LTR transcript RNA in the cytoplasm, conceivably only a single molecule of ORF2p is required for target-primed reverse transcription-integration in the nucleus. Why would the translation of ORF2 need to be controlled by such mechanisms? An -excess- of ORF2p could result in disadvantageous levels of genome instability by, for example, enhancing short, interspersed, element SINE retrotransposition and the generation of processed pseudogenes. If so, the acquisition of mechanisms—such as 2A—to control ORF2p biogenesis would be advantageous.



Author: Luke, Garry A; Roulston, Claire; Odon, Valerie; de Felipe, Pablo; Sukhodub, Andriy; Ryan, Martin D

Source: https://archive.org/







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