Vander Kooi Craig W, Ohi Melanie D, Rosenberg Joshua A, Oldham Michael L, Newcomer Marcia E, Gould Kathleen L, Chazin Walter J
Department of Biochemistry, Vanderbilt University, Nashville, Tennessee 37232, USA.
Biochemistry. 2006 Jan 10;45(1):121-30. doi: 10.1021/bi051787e.
Prp19 is an essential splicing factor and a member of the U-box family of E3 ubiquitin ligases. Prp19 forms a tetramer via a central coiled-coil domain. Here, we show the U-box domain of Prp19 exists as a dimer within the context of the Prp19 tetramer. A high-resolution structure of the homodimeric state of the Prp19 U-box was determined by X-ray crystallography. Mutation of the U-box dimer interface abrogates U-box dimer formation and is lethal in vivo. The structure of the U-box dimer enables construction of a complete model of Prp19 providing insights into how the tetrameric protein functions as an E3 ligase. Finally, comparison of the Prp19 U-box homodimer with the heterodimeric complex of BRCA1/BARD1 RING-finger domains uncovers a common architecture for a family of oligomeric U-box and RING-finger E3 ubiquitin ligases, which has mechanistic implications for E3 ligase-mediated polyubiquitination and E4 polyubiquitin ligases.
Prp19是一种必需的剪接因子，也是E3泛素连接酶的U-box家族成员。Prp19通过中央卷曲螺旋结构域形成四聚体。在此，我们表明Prp19的U-box结构域在Prp19四聚体的背景下以二聚体形式存在。通过X射线晶体学确定了Prp19 U-box同二聚体状态的高分辨率结构。U-box二聚体界面的突变消除了U-box二聚体的形成，并且在体内是致死的。U-box二聚体的结构使得能够构建Prp19的完整模型，从而深入了解四聚体蛋白如何作为E3连接酶发挥作用。最后，将Prp19 U-box同二聚体与BRCA1/BARD1环指结构域的异二聚体复合物进行比较，揭示了寡聚U-box和环指E3泛素连接酶家族的共同结构，这对E3连接酶介导的多聚泛素化和E4多聚泛素连接酶具有机制上的启示。
