Structural Basis of an N-Degron Adaptor with More Stringent Specificity.
Structural Basis of an N-Degron Adaptor with More Stringent Specificity.
复制标题
具有更严格特异性的 N-Degron 适配器的结构基础。
DOI：
10.1016/j.str.2015.12.008
复制
发表时间：
2016
期刊：
影响因子：
--
通讯作者：
Baker,TaniaA
中科院分区：
文献类型：
--
作者：
Stein,BenjaminJ;Grant,RobertA;Sauer,RobertT;Baker,TaniaA
N-端规则规定蛋白质的N-端残基决定其半衰期。在细菌中，CLPS接头通过识别含有特定N-末端残基的蛋白质并将它们运送到ClpAP AAA+蛋白酶来介导N-末端规则的降解。与大多数细菌分支不同的是，许多α蛋白细菌编码两个CLP类似物，ClpS1和ClpS2。在这里，我们证明了来自农杆菌的ClpS1和ClpS2都向ClpA递送N-末端规则底物，但ClpS2具有更严格的结合特异性，只识别典型细菌N-末端规则残基的一部分。这种增强的特异性的基础是ClpS2的晶体结构，有和没有配体，以及结构导向的突变，揭示了蛋白质构象的变化和底物结合口袋中的重塑。我们发现ClpS1和ClpS2在生长过程中有不同的表达，并得出结论，使用多个CLPS对映体的使用允许在底物识别水平上微调N-末端规则的降解。
The N-end rule dictates that a protein's N-terminal residue determines its half-life. In bacteria, the ClpS adaptor mediates N-end-rule degradation, by recognizing proteins bearing specific N-terminal residues and delivering them to the ClpAP AAA+ protease. Unlike most bacterial clades, many α-proteobacteria encode two ClpS paralogs, ClpS1 and ClpS2. Here, we demonstrate that both ClpS1 and ClpS2 fromA. tumefaciensdeliver N-end-rule substrates to ClpA, but ClpS2 has more stringent binding specificity, recognizing only a subset of the canonical bacterial N-end-rule residues. The basis of this enhanced specificity is addressed by crystal structures of ClpS2, with and without ligand, and structure-guided mutagenesis, revealing protein conformational changes and remodeling in the substrate-binding pocket. We find that ClpS1 and ClpS2 are differentially expressed during growth inA. tumefaciensand conclude that the use of multiple ClpS paralogs allows fine-tuning of N-end-rule degradation at the level of substrate recognition.