Coincident Hfq binding and RNase E cleavage sites on mRNA and small regulatory RNAs
Coincident Hfq binding and RNase E cleavage sites on mRNA and small regulatory RNAs
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作者：
Moll, I;Afonyushkin, T;Bläsi, U
大肠杆菌RNA分子伴侣Hfq最初是作为噬菌体Q β复制酶的辅助因子而被发现的。最近的研究表明，Hfq通过与ompA mRNA和小RNA（sRNA）的相互作用在细胞生理学中发挥作用，其中一些参与翻译调控。尽管它们在一定条件下是稳定的，但E. coli sRNA含有推定的RNase E识别位点，即富含A/U的序列和相邻的茎环结构。我们在本文中表明，RNase E切割位点与E的5 '非翻译区中的Hfq结合位点一致。coli ompA mRNA以及sRNA中的DsrA.同样，Hfq保护RyhB RNA免受RNA酶E的体外切割。这些体外数据得到了RNase E突变株中DsrA和RyhB sRNA丰度增加以及它们在hfq（-）菌株中稳定性降低的支持。通常认为RNA伴侣Hfq促进或促进sRNA与其mRNA靶之间的相互作用。这项研究揭示了Hfq的另一个作用，即保护sRNA免受核酸内切攻击。
The Escherichia coli RNA chaperone Hfq was discovered originally as an accessory factor of the phage Qbeta replicase. More recent work suggested a role of Hfq in cellular physiology through its interaction with ompA mRNA and small RNAs (sRNAs), some of which are involved in translational regulation. Despite their stability under certain conditions, E. coli sRNAs contain putative RNase E recognition sites, that is, A/U-rich sequences and adjacent stem-loop structures. We show herein that an RNase E cleavage site coincides with the Hfq-binding site in the 5'-untranslated region of E. coli ompA mRNA as well as with that in the sRNA, DsrA. Likewise, Hfq protects RyhB RNA from in vitro cleavage by RNase E. These in vitro data are supported by the increased abundance of DsrA and RyhB sRNAs in an RNase E mutant strain as well as by their decreased stability in a hfq(-) strain. It is commonly believed that the RNA chaperone Hfq facilitates or promotes the interaction between sRNAs and their mRNA targets. This study reveals another role for Hfq, that is, protection of sRNAs from endonucleolytic attack.