Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học 'Respiratory Research cung cấp cho các bạn kiến thức về ngành y đề tài: Structural features in the Rous sarcoma virus RNA stability element are necessary for sensing the correct termination codon. | Withers and Beemon Retrovirology 2010 7 65 http content 7 1 65 RETROVIROLOGY RESEARCH Open Access Structural features in the Rous sarcoma virus RNA stability element are necessary for sensing the correct termination codon Johanna B Withers Karen L Beemon Abstract Background Nonsense-mediated mRNA decay NMD is an mRNA quality control mechanism that selectively recognizes and targets for degradation mRNAs containing premature termination codons. Retroviral full-length RNA is presented to the host translation machinery with characteristics rarely observed among host cell mRNAs a long 3 UTR retained introns and multiple open reading frames. As a result the viral RNA is predicted to be recognized by the host NMD machinery and degraded. In the case of the Rous sarcoma virus RSV we identified a stability element RSE which resides immediately downstream of the gag termination codon and facilitates NMD evasion. Results We defined key RNA features of the RSE through directed mutagenesis of the virus. These data suggest that the minimal RSE is 155 nucleotides nts and functions independently of the nucleotide sequence of the stop codon or the first nucleotide following the stop codon. Further data suggested that the 3 UTRs of the RSV pol and src may also function as stability elements. Conclusions We propose that these stability elements in RSV may be acting as NMD insulators to mask the preceding stop codon from the NMD machinery. Background Nonsense-mediated mRNA decay NMD selectively recognizes and targets for degradation mRNAs containing premature termination codons. This mRNA quality control mechanism prevents potentially deleterious dominant negative effects of truncated proteins that accumulate if aberrant mRNAs are not degraded 1-4 . In mammalian cells NMD proteins can efficiently identify a termination codon as premature if the stop codon resides at least 50 nucleotides upstream of the terminal exon-exon junction 5 6 . When introns are removed .
