Ubiquitylation by the Ltn1 E3 ligase protects 60S ribosomes from starvation-induced selective autophagy.
Ubiquitylation by the Ltn1 E3 ligase protects 60S ribosomes from starvation-induced selective autophagy.
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DOI：
10.1083/jcb.201308139
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发表时间：
2014-03-17
期刊：
影响因子：
--
通讯作者：
Dargemont C
中科院分区：
文献类型：
--
作者：
Ossareh-Nazari B;Niño CA;Bengtson MH;Lee JW;Joazeiro CA;Dargemont C
E3连接酶Ltd n1和去泛素化酶Ubp3-Bre5滴定核糖体亚基泛素化水平，从而决定核糖体蛋白因营养供应和蛋白质翻译水平而被核噬菌体降解的速率。自噬是蛋白质或细胞器被自噬小体吞噬并运送给空泡/溶酶体降解的过程，诱导自噬是为了确保在饥饿和其他胁迫下存活。最近描述了一种选择性的自噬途径，即在酵母中由氮饥饿引起的60S核糖体亚基的自噬途径--核噬菌体，它需要Ubp3-Bre5脱泛素化酶。这一发现表明，E3连接酶作用于上游，无论是抑制这一过程还是提供最初所需的信号。在这篇文章中，我们证明了与翻译监视有关的60S核糖体相关E3基因Ltn1/Rkr1作为60S核糖体亚单位核噬菌体的抑制因子，并被Ubp3拮抗。核糖体蛋白Rpl25是一个相关的目标。它的泛素化依赖于Ltn1，Ubp3被逆转，其泛素化位点的突变使得核噬菌体对Ubp3的依赖程度降低。一致地，在饥饿后，Ltn1-而不是Ubp3-的表达迅速下降，推测是为了允许核噬菌体继续进行。因此，Ltn1和Ubp3-Bre5可能有助于使噬核体活性适应营养供应和蛋白质翻译。
The E3 ligase Ltn1 and the deubiquitylase Ubp3-Bre5 titrate the level of ribosomal subunit ubiquitylation and thereby set the rate of ribosomal protein degradation by ribophagy in response to nutrient supply and the level of protein translation. Autophagy, the process by which proteins or organelles are engulfed by autophagosomes and delivered for vacuolar/lysosomal degradation, is induced to ensure survival under starvation and other stresses. A selective autophagic pathway for 60S ribosomal subunits elicited by nitrogen starvation in yeast—ribophagy—was recently described and requires the Ubp3-Bre5 deubiquitylating enzyme. This discovery implied that an E3 ligases act upstream, whether inhibiting the process or providing an initial required signal. In this paper, we show that Ltn1/Rkr1, a 60S ribosome-associated E3 implicated in translational surveillance, acts as an inhibitor of 60S ribosomal subunit ribophagy and is antagonized by Ubp3. The ribosomal protein Rpl25 is a relevant target. Its ubiquitylation is Ltn1 dependent and Ubp3 reversed, and mutation of its ubiquitylation site rendered ribophagy less dependent on Ubp3. Consistently, the expression of Ltn1—but not Ubp3—rapidly decreased after starvation, presumably to allow ribophagy to proceed. Thus, Ltn1 and Ubp3-Bre5 likely contribute to adapt ribophagy activity to both nutrient supply and protein translation.
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DOI：
10.1073/pnas.0812819106
发表时间：
2009-02-17
影响因子：
11.1
作者：
Chu, Jessie;Hong, Nancy A.;Kay, Steve A.
通讯作者：
Kay, Steve A.
影响因子：
11.8
作者：
Shintani, T;Huang, WP;Klionsky, DJ
通讯作者：
Klionsky, DJ
影响因子：
13.3
作者：
Kraft, Claudine;Peter, Matthias
通讯作者：
Peter, Matthias
影响因子：
16
作者：
Shao, Sichen;von der Malsburg, Karina;Hegde, Ramanujan S.
通讯作者：
Hegde, Ramanujan S.
影响因子：
21.3
作者：
Vitaliano-Prunier, Adeline;Menant, Alexandra;Dargemont, Catherine
通讯作者：
Dargemont, Catherine