Dipartimento di Scienze biomolecolari e Biotecnologie, Università degli Studi di Milano, Milano, Italy.
Nucleic Acids Res. 2011 Sep 1;39(17):7702-15. doi: 10.1093/nar/gkr417. Epub 2011 Jun 17.
S1 is an 'atypical' ribosomal protein weakly associated with the 30S subunit that has been implicated in translation, transcription and control of RNA stability. S1 is thought to participate in translation initiation complex formation by assisting 30S positioning in the translation initiation region, but little is known about its role in other RNA transactions. In this work, we have analysed in vivo the effects of different intracellular S1 concentrations, from depletion to overexpression, on translation, decay and intracellular distribution of leadered and leaderless messenger RNAs (mRNAs). We show that the cspE mRNA, like the rpsO transcript, may be cleaved by RNase E at multiple sites, whereas the leaderless cspE transcript may also be degraded via an alternative pathway by an unknown endonuclease. Upon S1 overexpression, RNase E-dependent decay of both cspE and rpsO mRNAs is suppressed and these transcripts are stabilized, whereas cleavage of leaderless cspE mRNA by the unidentified endonuclease is not affected. Overall, our data suggest that ribosome-unbound S1 may inhibit translation and that part of the Escherichia coli ribosomes may actually lack S1.
S1 是一种与 30S 亚基弱结合的“非典型”核糖体蛋白，它与翻译、转录和 RNA 稳定性控制有关。S1 被认为通过协助 30S 在翻译起始区的定位参与翻译起始复合物的形成，但它在其他 RNA 交易中的作用知之甚少。在这项工作中，我们分析了不同细胞内 S1 浓度（从耗尽到过表达）对有先导和无先导的信使 RNA（mRNA）翻译、衰减和细胞内分布的影响。我们表明，cspE mRNA 可能像 rpsO 转录物一样，可由 RNase E 在多个位点切割，而无先导的 cspE 转录物也可能通过未知的内切核酸酶通过替代途径降解。在 S1 过表达时，依赖于 RNase E 的 cspE 和 rpsO mRNA 的衰减被抑制，这些转录物被稳定，而无先导的 cspE mRNA 被不明内切核酸酶切割不受影响。总的来说，我们的数据表明，核糖体非结合的 S1 可能抑制翻译，而部分大肠杆菌核糖体实际上可能缺乏 S1。
