在核中的降解介导蛋白质质量控制
Richard G Gardner1, Zara W Nelson, Daniel E Gottschling
1Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA.
Cell
|March 31, 2005
概括
科学家们在酵母中发现了一种核蛋白降解系统,由San1p调解,可以消除异常蛋白质. 这一发现填补了细胞蛋白质质量控制的空白,防止细胞核中有害的蛋白质积聚.
科学领域:
- 细胞生物学 细胞生物学
- 分子生物学分子生物学
- 生物化学 生物化学
背景情况:
- 蛋白质质量控制 (PQC) 系统对于细胞功能至关重要,可以清除受损或错误折叠的蛋白质.
- 虽然PQC通路存在于各种细胞区,但仍未发现用于细胞核的专用系统.
- 异常的核蛋白质可以积累并对细胞过程产生有害影响.
研究的目的:
- 在Saccharomyces cerevisiae的核中识别和描述一种新的蛋白质降解系统.
- 阐明核蛋白质质量控制的分子组成部分和机制.
- 了解核蛋白降解在预防细胞压力的功能意义.
主要方法:
- 利用了酵母遗传学和分子生物学技术.
- 研究了San1p的作用,一个假定的无素蛋白联酶,在核蛋白循环中发挥作用.
- 评估了突变核蛋白在SAN1.1存在或不存在的情况下的全域化和蛋白质体降解.
- 检查了San1p的细胞局部化和功能要求.
主要成果:
- 发现了一种核ubiquitin-protein结合酶,San1p,它调解了异常核蛋白的降解.
- 与Cdc34p和Ubc1p一起,San1p针对特定的突变蛋白进行无处不在和蛋白质破坏.
- San1p表现出高特异性,降解突变蛋白质,同时保留它们的野生类型对应物.
- 失去SAN1功能导致慢性细胞应激反应,突出其PQC作用.
结论:
- 通过San1p介导的降解代表了第一个在酵母中发现的核蛋白质质量控制系统.
- 这条通路作为一个关键的防御,防止核中有毒异常蛋白质的积累.
- 这些发现表明,其他真核生物体中存在类似的核PQC系统.
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The Upf proteins that carry out nonsense-mediated decay (NMD) are found in all eukaryotic organisms, including humans. Each protein has an individual role, but they need to work in collaboration. Upf1 is an ATP-dependent RNA helicase that unwinds the RNA helix. Because Upf1 can unwind any RNA, Upf2 and Upf3 are required to help Upf1 discriminate between nonsense and normal mRNAs.
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