Seong Ki Moon, Baek Je-Hyun, Yu Myeong-Hee, Kim Joon
Laboratory of Biochemistry, School of Life Sciences and Biotechnology, Korea University, Seoul 136-701, Republic of Korea.
FEBS Lett. 2007 May 29;581(13):2567-73. doi: 10.1016/j.febslet.2007.04.064. Epub 2007 Apr 30.
The 26S proteasome, composed of the 20S core and 19S regulatory complexes, is important for the turnover of polyubiquitinated proteins. Each subunit of the complex plays a special role in proteolytic function, including substrate recruitment, deubiquitination, and structural contribution. To assess the function of some non-essential subunits in the 26S proteasome, we isolated the 26S proteasome from deletion strains of RPN13 and RPN14 using TAP affinity purification. The stability of Gcn4p and the accumulation of ubiquitinated Gcn4p were significantly increased, but the affinity in the recognition of proteasome was decreased. In addition, the subcomplexes of the isolated 26S proteasomes from deletion mutants were less stable than that of the wild type. Taken together, our findings indicate that Rpn13p and Rpn14p are involved in the efficient recognition of 26S proteasome for the proteolysis of ubiquitinated Gcn4p.
由20S核心颗粒和19S调节复合物组成的26S蛋白酶体对于多聚泛素化蛋白的周转至关重要。该复合物的每个亚基在蛋白水解功能中都发挥着特殊作用，包括底物招募、去泛素化以及结构贡献。为了评估26S蛋白酶体中一些非必需亚基的功能，我们使用TAP亲和纯化法从RPN13和RPN14缺失菌株中分离出26S蛋白酶体。Gcn4p的稳定性和泛素化Gcn4p的积累显著增加，但对蛋白酶体识别的亲和力降低。此外，从缺失突变体中分离出的26S蛋白酶体的亚复合物比野生型的稳定性更低。综上所述，我们的研究结果表明，Rpn13p和Rpn14p参与了26S蛋白酶体对泛素化Gcn4p进行蛋白水解的有效识别。
