A novel recognition site for polyubiquitin and ubiquitin-like signals in an unexpected region of proteasomal subunit Rpn1.
A novel recognition site for polyubiquitin and ubiquitin-like signals in an unexpected region of proteasomal subunit Rpn1.
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DOI：
10.1016/j.jbc.2021.101052
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发表时间：
2021-09
期刊：
影响因子：
--
通讯作者：
Fushman D
中科院分区：
文献类型：
--
作者：
Boughton AJ;Liu L;Lavy T;Kleifeld O;Fushman D
泛素（Ub）-蛋白酶体系统是真核生物中维持蛋白质稳态的主要机制，但其组分的潜在信号事件和特异性知之甚少。预定降解的蛋白质用共价连接的多聚Ub链标记，随后通常在含有Ub样结构域的穿梭蛋白的帮助下递送至蛋白酶体。这一降解途径充满了明显的冗余-以各种长度和不同结构的多聚泛素链，多种穿梭蛋白和至少三种蛋白酶体受体的形式。此外，最大的蛋白酶体受体，Rpn 1，包含一个已知的多聚泛素和穿梭蛋白的结合位点，虽然最近有几项研究提出了存在一个额外的未表征的网站。在这里，使用NMR光谱，光交联，质谱和诱变的组合，我们表明，Rpn 1确实包含另一个识别位点，表现出亲和力和结合偏好的多聚泛素和UB样信号相媲美的已知的结合位点在Rpn 1。令人惊讶的是，这个新的网站是位于N-末端部分的Rpn 1，一个区域以前推测是缺乏功能。我们确定了一段相邻的螺旋作为这个以前未表征的结合位点的位置，其空间接近性和相似的性质，以已知的结合位点在Rpn 1建议的多价信号识别的可能性，在溶剂暴露的表面Rpn 1。这些发现为信号识别过程提供了新的机制见解，这些信号识别过程是Ub-蛋白酶体系统的核心。
The ubiquitin (Ub)–proteasome system is the primary mechanism for maintaining protein homeostasis in eukaryotes, yet the underlying signaling events and specificities of its components are poorly understood. Proteins destined for degradation are tagged with covalently linked polymeric Ub chains and subsequently delivered to the proteasome, often with the assistance of shuttle proteins that contain Ub-like domains. This degradation pathway is riddled with apparent redundancy—in the form of numerous polyubiquitin chains of various lengths and distinct architectures, multiple shuttle proteins, and at least three proteasomal receptors. Moreover, the largest proteasomal receptor, Rpn1, contains one known binding site for polyubiquitin and shuttle proteins, although several studies have recently proposed the existence of an additional uncharacterized site. Here, using a combination of NMR spectroscopy, photocrosslinking, mass spectrometry, and mutagenesis, we show that Rpn1 does indeed contain another recognition site that exhibits affinities and binding preferences for polyubiquitin and Ub-like signals comparable to those of the known binding site in Rpn1. Surprisingly, this novel site is situated in the N-terminal section of Rpn1, a region previously surmised to be devoid of functionality. We identified a stretch of adjacent helices as the location of this previously uncharacterized binding site, whose spatial proximity and similar properties to the known binding site in Rpn1 suggest the possibility of multivalent signal recognition across the solvent-exposed surface of Rpn1. These findings offer new mechanistic insights into signal recognition processes that are at the core of the Ub–proteasome system.
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影响因子：
4.3
作者：
D'Onofrio, Mariapina;Gianolio, Eliana;Assfalg, Michael
通讯作者：
Assfalg, Michael
影响因子：
8.6
作者：
Chojnacki M;Mansour W;Hameed DS;Singh RK;El Oualid F;Rosenzweig R;Nakasone MA;Yu Z;Glaser F;Kay LE;Fushman D;Ovaa H;Glickman MH
通讯作者：
Glickman MH
影响因子：
5.6
作者：
Haririnia, Aydin;D'Onofrio, Mariapina;Fushman, David
通讯作者：
Fushman, David
影响因子：
2.9
作者：
MANAVALAN, P;JOHNSON, WC
通讯作者：
JOHNSON, WC
DOI：
10.1002/prot.340230412
发表时间：
1995-12-01
期刊：
PROTEINS-STRUCTURE FUNCTION AND GENETICS
影响因子：
--
作者：
Frishman, D;Argos, P
通讯作者：
Argos, P