Sakata Tomoko, Fujii Kotaro, Ohno Mutsuhito, Kitabatake Makoto
Institute for Virus Research, Kyoto University, Shogoin-Kawaharacho 53, Sakyo-ku, Kyoto 606-8507, Japan.
Institute for Virus Research, Kyoto University, Shogoin-Kawaharacho 53, Sakyo-ku, Kyoto 606-8507, Japan.
Biochem Biophys Res Commun. 2015 Jan 30;457(1):90-4. doi: 10.1016/j.bbrc.2014.12.072. Epub 2014 Dec 19.
Nonfunctional mutant ribosomal RNAs in 40S or 60S subunits are selectively degraded in eukaryotic cells (nonfunctional rRNA decay, NRD). We previously reported that NRD of 25S rRNA required cullin-E3 ligase Rtt101 and its associating factor Mms1, both of which are involved in DNA repair. Although Mms22, an accessory component of the E3 complex, was suggested to direct the E3 complex to DNA repair, the factor that directs the complex to 25S NRD currently remains unknown. We herein demonstrated that another accessory component, Crt10 was required for 25S NRD, but not for DNA repair, suggesting that this accessory component specifies the function of the E3 complex differently. We also identified two distinct Crt10-containing E3 complexes, one of which contained the Paf1 complex, a Pol-II binding complex that modulates the transcription of stress-related genes. Our results showed the convergence of multiple pathways for stresses that harm nucleic acids and provided a molecular framework for the substrate diversity of the E3 complex.
真核细胞中，40S或60S亚基的无功能突变核糖体RNA会被选择性降解（无功能rRNA降解，NRD）。我们之前报道过，25S rRNA的NRD需要泛素连接酶Rtt101及其相关因子Mms1，二者均参与DNA修复。虽然E3复合物的辅助成分Mms22被认为可将E3复合物导向DNA修复，但目前仍不清楚将该复合物导向25S NRD的因子是什么。我们在此证明，另一个辅助成分Crt10是25S NRD所必需的，但不是DNA修复所必需的，这表明该辅助成分以不同方式指定E3复合物的功能。我们还鉴定出两种不同的含Crt10的E3复合物，其中一种含有Paf1复合物，这是一种与Pol-II结合的复合物，可调节应激相关基因的转录。我们的结果显示了多种损害核酸的应激途径的汇聚，并为E3复合物的底物多样性提供了分子框架。
