Bühler Marc, Spies Noah, Bartel David P, Moazed Danesh
Department of Cell Biology, 240 Longwood Avenue, Harvard Medical School, Boston, Massachusetts 02115 USA.
Nat Struct Mol Biol. 2008 Oct;15(10):1015-23. doi: 10.1038/nsmb.1481. Epub 2008 Sep 7.
In the fission yeast Schizosaccharomyces pombe, the RNA interference (RNAi) machinery is required to generate small interfering RNAs (siRNAs) that mediate heterochromatic gene silencing. Efficient silencing also requires the TRAMP complex, which contains the noncanonical Cid14 poly(A) polymerase and targets aberrant RNAs for degradation. Here we use high-throughput sequencing to analyze Argonaute-associated small RNAs (sRNAs) in both the presence and absence of Cid14. Most sRNAs in fission yeast start with a 5' uracil, and we argue these are loaded most efficiently into Argonaute. In wild-type cells most sRNAs match to repeated regions of the genome, whereas in cid14Delta cells the sRNA profile changes to include major new classes of sRNAs originating from ribosomal RNAs and a tRNA. Thus, Cid14 prevents certain abundant RNAs from becoming substrates for the RNAi machinery, thereby freeing the RNAi machinery to act on its proper targets.
在裂殖酵母粟酒裂殖酵母中，RNA干扰（RNAi）机制用于生成介导异染色质基因沉默的小干扰RNA（siRNA）。有效的沉默还需要TRAMP复合物，该复合物包含非经典的Cid14聚腺苷酸聚合酶，并靶向异常RNA进行降解。在这里，我们使用高通量测序来分析在有和没有Cid14的情况下与AGO蛋白相关的小RNA（sRNA）。裂殖酵母中的大多数sRNA以5'尿嘧啶开头，我们认为这些sRNA能最有效地装载到AGO蛋白中。在野生型细胞中，大多数sRNA与基因组的重复区域匹配，而在cid14Δ细胞中，sRNA谱发生变化，包括源自核糖体RNA和一种tRNA的主要新sRNA类别。因此，Cid14可防止某些丰富的RNA成为RNAi机制的底物，从而使RNAi机制能够作用于其合适的靶标。
