Schwarz S E, Matuschewski K, Liakopoulos D, Scheffner M, Jentsch S
Deutsches Krebsforschungszentrum, Heidelberg, Germany.
Proc Natl Acad Sci U S A. 1998 Jan 20;95(2):560-4. doi: 10.1073/pnas.95.2.560.
The ubiquitin-like protein SMT3 from Saccharomyces cerevisiae and SUMO-1, its mammalian homolog, can be covalently attached to other proteins posttranslationally. Conjugation of ubiquitin requires the activities of ubiquitin-activating (E1) and -conjugating (E2) enzymes and proceeds via thioester-linked enzyme-ubiquitin intermediates. Herein we show that UBC9, one of the 13 different E2 enzymes from yeast, is required for SMT3 conjugation in vivo. Moreover, recombinant yeast and mammalian UBC9 enzymes were found to form thioester complexes with SMT3 and SUMO-1, respectively. This suggests that UBC9 functions as an E2 in a SMT3/SUMO-1 conjugation pathway analogous to ubiquitin-conjugating enzymes. The role of yeast UBC9 in cell cycle progression may thus be mediated through its SMT3 conjugation activity.
来自酿酒酵母的泛素样蛋白SMT3及其哺乳动物同源物SUMO-1可在翻译后共价连接到其他蛋白质上。泛素的缀合需要泛素激活酶（E1）和缀合酶（E2）的活性，并通过硫酯连接的酶-泛素中间体进行。在此我们表明，酵母中13种不同E2酶之一的UBC9在体内SMT3缀合过程中是必需的。此外，发现重组酵母和哺乳动物UBC9酶分别与SMT3和SUMO-1形成硫酯复合物。这表明UBC9在类似于泛素缀合酶的SMT3/SUMO-1缀合途径中作为E2发挥作用。因此，酵母UBC9在细胞周期进程中的作用可能是通过其SMT3缀合活性介导的。
