Department of Microbiology, National Taiwan University, Taipei, Taiwan.
Biochem Biophys Res Commun. 2010 Mar 5;393(2):297-302. doi: 10.1016/j.bbrc.2010.02.003. Epub 2010 Feb 6.
The small subunit (SSU) processome is an evolutionarily conserved ribonucleoprotein (RNP) complex that consists of U3 snoRNA and at least 40 protein components. The SSU processome is required for the generation of 18S rRNA in the budding yeast Saccharomyces cerevisiae. In this study we demonstrate that two essential components of the SSU processome, Utp8p and Utp9p, must interact directly for the SSU processome to function properly. Disruption of the Utp8p-Utp9p interaction by mutation of the respective interacting domain led to a compromised ability of yeast cells to process 35S pre-rRNA into 18S pre-rRNA. Loss of the Utp8p-Utp9p interaction also led to a decrease in the amount of Utp8p that interacted with U3 small nucleolar RNAs (snoRNAs) but did not affect the amount of Utp9p bound to U3 snoRNA, suggesting that Utp8p associates with the SSU processome by virtue of its interaction with Utp9p. Together, our data support a model where Utp8p and Utp9p must interact directly and functionally in the U3-containing SSU processome for optimal rRNA biosynthesis to occur in budding yeast.
小亚基（SSU）加工体是一种进化上保守的核糖核蛋白（RNP）复合物，由 U3 snoRNA 和至少 40 个蛋白组成。SSU 加工体是酿酒酵母 Saccharomyces cerevisiae 18S rRNA 生成所必需的。在这项研究中，我们证明了 SSU 加工体的两个必需成分，Utp8p 和 Utp9p，必须直接相互作用，SSU 加工体才能正常发挥功能。通过突变相互作用域破坏 Utp8p-Utp9p 相互作用，导致酵母细胞将 35S 前 rRNA 加工成 18S 前 rRNA 的能力受损。Utp8p-Utp9p 相互作用的丧失也导致与 U3 小核仁 RNA（snoRNA）相互作用的 Utp8p 量减少，但不影响与 U3 snoRNA 结合的 Utp9p 量，表明 Utp8p 凭借与 Utp9p 的相互作用与 SSU 加工体结合。总之，我们的数据支持这样一种模型，即 Utp8p 和 Utp9p 必须在含有 U3 的 SSU 加工体中直接相互作用和发挥功能，才能使酿酒酵母中的 rRNA 生物合成达到最佳状态。
