Sharma Sunny, Langhendries Jean-Louis, Watzinger Peter, Kötter Peter, Entian Karl-Dieter, Lafontaine Denis L J
Institute of Molecular Biosciences, Goethe University, 60438 Frankfurt am Main, Germany RNA Molecular Biology, F.R.S./FNRS, Université Libre de Bruxelles, B-6041 Charleroi-Gosselies, Belgium.
RNA Molecular Biology, F.R.S./FNRS, Université Libre de Bruxelles, B-6041 Charleroi-Gosselies, Belgium.
Nucleic Acids Res. 2015 Feb 27;43(4):2242-58. doi: 10.1093/nar/gkv075. Epub 2015 Feb 4.
The function of RNA is subtly modulated by post-transcriptional modifications. Here, we report an important crosstalk in the covalent modification of two classes of RNAs. We demonstrate that yeast Kre33 and human NAT10 are RNA cytosine acetyltransferases with, surprisingly, specificity toward both 18S rRNA and tRNAs. tRNA acetylation requires the intervention of a specific and conserved adaptor: yeast Tan1/human THUMPD1. In budding and fission yeasts, and in human cells, we found two acetylated cytosines on 18S rRNA, one in helix 34 important for translation accuracy and another in helix 45 near the decoding site. Efficient 18S rRNA acetylation in helix 45 involves, in human cells, the vertebrate-specific box C/D snoRNA U13, which, we suggest, exposes the substrate cytosine to modification through Watson-Crick base pairing with 18S rRNA precursors during small subunit biogenesis. Finally, while Kre33 and NAT10 are essential for pre-rRNA processing reactions leading to 18S rRNA synthesis, we demonstrate that rRNA acetylation is dispensable to yeast cells growth. The inactivation of NAT10 was suggested to suppress nuclear morphological defects observed in laminopathic patient cells through loss of microtubules modification and cytoskeleton reorganization. We rather propose the effects of NAT10 on laminopathic cells are due to reduced ribosome biogenesis or function.
RNA的功能受到转录后修饰的精细调控。在此，我们报道了两类RNA共价修饰过程中的一个重要相互作用。我们证明酵母Kre33和人类NAT10是RNA胞嘧啶乙酰转移酶，令人惊讶的是，它们对18S rRNA和tRNA均具有特异性。tRNA乙酰化需要一种特定且保守的衔接蛋白的介入：酵母Tan1/人类THUMPD1。在芽殖酵母、裂殖酵母和人类细胞中，我们在18S rRNA上发现了两个乙酰化的胞嘧啶，一个在对翻译准确性至关重要的螺旋34中，另一个在解码位点附近的螺旋45中。在人类细胞中，螺旋45中高效的18S rRNA乙酰化涉及脊椎动物特有的盒C/D小核仁RNA U13，我们认为，在小亚基生物合成过程中，它通过与18S rRNA前体的沃森-克里克碱基配对使底物胞嘧啶暴露于修饰之下。最后，虽然Kre33和NAT10对于导致18S rRNA合成的前体rRNA加工反应至关重要，但我们证明rRNA乙酰化对于酵母细胞生长是可有可无的。有人提出NAT10的失活通过微管修饰的丧失和细胞骨架重组来抑制在核纤层蛋白病患者细胞中观察到的核形态缺陷。我们更倾向于认为NAT10对核纤层蛋白病细胞的影响是由于核糖体生物合成或功能的降低。
