Weems Juston C, Slaughter Brian D, Unruh Jay R, Boeing Stefan, Hall Shawn M, McLaird Merry B, Yasukawa Takashi, Aso Teijiro, Svejstrup Jesper Q, Conaway Joan W, Conaway Ronald C
From the Stowers Institute for Medical Research, Kansas City, Missouri 64110.
the Mechanisms of Transcription Laboratory, The Francis Crick Institute, Clare Hall Laboratories, South Mimms EN6 3LD, United Kingdom.
J Biol Chem. 2017 Apr 21;292(16):6431-6437. doi: 10.1074/jbc.C117.777946. Epub 2017 Mar 14.
Elongin A performs dual functions as the transcriptionally active subunit of RNA polymerase II (Pol II) elongation factor Elongin and as the substrate recognition subunit of a Cullin-RING E3 ubiquitin ligase that ubiquitylates Pol II in response to DNA damage. Assembly of the Elongin A ubiquitin ligase and its recruitment to sites of DNA damage is a tightly regulated process induced by DNA-damaging agents and α-amanitin, a drug that induces Pol II stalling. In this study, we demonstrate (i) that Elongin A and the ubiquitin ligase subunit CUL5 associate in cells with the Cockayne syndrome B (CSB) protein and (ii) that this interaction is also induced by DNA-damaging agents and α-amanitin. In addition, we present evidence that the CSB protein promotes stable recruitment of the Elongin A ubiquitin ligase to sites of DNA damage. Our findings are consistent with the model that the Elongin A ubiquitin ligase and the CSB protein function together in a common pathway in response to Pol II stalling and DNA damage.
延伸因子A（Elongin A）具有双重功能，既是RNA聚合酶II（Pol II）延伸因子Elongin的转录活性亚基，又是一种Cullin-RING E3泛素连接酶的底物识别亚基，该连接酶可在DNA损伤时使Pol II泛素化。Elongin A泛素连接酶的组装及其向DNA损伤位点的募集是一个受到严格调控的过程，由DNA损伤剂和α-鹅膏蕈碱（一种诱导Pol II停滞的药物）诱导。在本研究中，我们证明：（i）Elongin A和泛素连接酶亚基CUL5在细胞中与科凯恩综合征B（CSB）蛋白相关联；（ii）这种相互作用也由DNA损伤剂和α-鹅膏蕈碱诱导。此外，我们提供证据表明，CSB蛋白促进Elongin A泛素连接酶稳定募集到DNA损伤位点。我们的研究结果与以下模型一致，即Elongin A泛素连接酶和CSB蛋白在应对Pol II停滞和DNA损伤的共同途径中共同发挥作用。
