tailieunhanh - Báo cáo y học: " The amazing world of bacterial structured RNAs"

Tuyển tập các báo cáo nghiên cứu về y học được đăng trên tạp chí y học Wertheim cung cấp cho các bạn kiến thức về ngành y đề tài: The amazing world of bacterial structured RNAs. | Westhof Genome Biology 2010 11 108 http 2010 11 3 108 w Genome Biology RESEARCH HIGHLIGHT L__ The amazing world of bacterial structured RNAs Eric Westhof See related research article by Weinberg etal. http 2010 11 3 R31 Abstract The discovery of several new structured noncoding RNAs in bacterial and archaeal genomes and metagenomes raises burning questions about their biological and biochemical functions. Introduction The compact genomes of bacteria contain 10 to 15 noncoding DNA sequences which are transcribed into noncoding RNAs. Several classes of non-coding RNAs are small less than 80 to 150 nucleotides and act as post-transcriptional regulators by targeting mRNAs. Another large class of non-coding RNAs act in cis by binding structured elements in the 5 untranslated regions of mRNAs. Perhaps the best known are called riboswitches upon binding a metabolite the fold of the transcript is modified and this influences either the termination of transcription or the initiation of translation 1 . Some longer non-coding RNAs have also been detected in recent years. For example RNAIII present in several Gram-positive bacteria is 500 nucleotides long and contains structured regions framing an open-reading frame 2 . However two recent papers from Ron Breaker s group increase the number of large non-coding RNAs astonishingly 3 4 . Several new smaller non-coding RNAs are also identified. Strikingly most of the new noncoding RNAs are structurally very complex. The complexity of some of the larger ones seems similar to that of the large ribozymes such as the self-splicing group I and group II introns. These observations show once again how little we know about the microbial world a great proportion of these new non-coding RNAs were identified in metagenomes or in environmental DNA sequences. The search for non-coding RNAs The search for non-coding RNAs in genomes is far from trivial 5 . Even for homologous and functionally