Panasenko Olesya O, David Fabrice P A, Collart Martine A
Swiss Institute for Bioinformatics, University of Geneva, 1211 Geneva 4, Switzerland.
Genetics. 2009 Feb;181(2):447-60. doi: 10.1534/genetics.108.095422. Epub 2008 Dec 15.
In this work we addressed the role of ubiquitination in the function of the nascent polypeptide-associated complex (NAC), named EGD in the yeast Saccharomyces cerevisiae. To this end, we first identified the lysines residues required for ubiquitination of EGD/NAC. While simultaneous mutation of many lysines in the alpha-subunit of NAC (Egd2p) was required to abolish its ubiquitination, for the beta-subunit of NAC (Egd1p), mutation of K29 and K30 was sufficient. We determined that the ubiquitination of the two EGD subunits was coordinated, occurring during growth first on Egd1p and then on Egd2p. Egd2p was ubiquitinated earlier during growth if Egd1p could not be ubiquitinated. The use of mutants revealed the importance of EGD ubiqutination for its ribosome association and stability. Finally, our study demonstrated an interaction of EGD/NAC with the proteasome and revealed the importance of the Not4p E3 ligase, responsible for EGD/NAC ubiquitination, in this association.
在这项工作中，我们研究了泛素化在新生多肽相关复合物（NAC，在酿酒酵母中称为EGD）功能中的作用。为此，我们首先确定了EGD/NAC泛素化所需的赖氨酸残基。虽然需要同时突变NACα亚基（Egd2p）中的许多赖氨酸才能消除其泛素化，但对于NAC的β亚基（Egd1p），K29和K30的突变就足够了。我们确定两个EGD亚基的泛素化是协调进行的，在生长过程中首先发生在Egd1p上，然后发生在Egd2p上。如果Egd1p不能被泛素化，Egd2p在生长过程中会更早地被泛素化。突变体的使用揭示了EGD泛素化对其核糖体结合和稳定性的重要性。最后，我们的研究证明了EGD/NAC与蛋白酶体之间的相互作用，并揭示了负责EGD/NAC泛素化的Not4p E3连接酶在这种关联中的重要性。
