A slicer-mediated mechanism for repeat-associated siRNA 5′ end formation in Drosophila
A slicer-mediated mechanism for repeat-associated siRNA 5′ end formation in Drosophila
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DOI：
10.1126/science.1140494
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发表时间：
2007-03-16
期刊：
影响因子：
56.9
通讯作者：
Siomi, Mikiko C.
中科院分区：
文献类型：
--
作者：
Gunawardane, Lalith S.;Saito, Kuniaki;Siomi, Mikiko C.
在果蝇中，重复相关的小干扰rna （rasiRNAs）在种系中通过dicer非依赖性途径产生，并通过Argonautes的PIWI亚家族发挥作用，以确保逆转录转座子的沉默。我们对PIWI亚家族成员AGO3相关的小rna进行了测序。虽然PIWI的其他成员Aubergine （Aub）和PIWI与rasiRNAs相关主要来自逆转录转座子的反义链，但ago3相关的rasiRNAs主要来自义链。Aub-和piwi -相关的rasiRNAs在其5'端表现出对尿嘧啶的强烈偏好，而ago3相关的rasiRNAs在核苷酸10处表现出对腺嘌呤的强烈偏好。比较AGO3-和Aub-相关的rasiRNAs，发现它们的前10个核苷酸具有互补性。Aub和AGO3在体外表现出切片活性。这些数据支持一种模型，其中rasiRNA前体中5'末端的形成是由源自另一条链转录本的rasiRNA引导的，与PIWI的切片器活性一致。
In Drosophila, repeat-associated small interfering RNAs (rasiRNAs) are produced in the germ line by a Dicer-independent pathway and function through the PIWI subfamily of Argonautes to ensure silencing of retrotransposons. We sequenced small RNAs associated with the PIWI subfamily member AGO3. Although other members of PIWI, Aubergine (Aub) and Piwi, associated with rasiRNAs derived mainly from the antisense strand of retrotransposons, AGO3-associated rasiRNAs arose mainly from the sense strand. Aub- and Piwi-associated rasiRNAs showed a strong preference for uracil at their 5' ends, and AGO3-associated rasiRNAs showed a strong preference for adenine at nucleotide 10. Comparisons between AGO3- and Aub- associated rasiRNAs revealed pairs of rasiRNAs showing complementarities in their first 10 nucleotides. Aub and AGO3 exhibited Slicer activity in vitro. These data support a model in which formation of a 5' terminus within rasiRNA precursors is guided by rasiRNAs originating from transcripts of the other strand in concert with the Slicer activity of PIWI.