The ubiquitin-like protein Smt3p is activated for conjugation to other proteins by an Aos1p/Uba2p heterodimer
The ubiquitin-like protein Smt3p is activated for conjugation to other proteins by an Aos1p/Uba2p heterodimer
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DOI：
10.1093/emboj/16.18.5509
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发表时间：
1997-09-15
期刊：
影响因子：
11.4
通讯作者：
Blobel, G
中科院分区：
文献类型：
--
作者：
Johnson, ES;Schwienhorst, I;Blobel, G
SMT3 是酿酒酵母必需基因，编码与哺乳动物泛素样蛋白 SUMO-1 相似的 11.5 kDa 蛋白。我们发现 Smt3p 与 SUMO-1 和泛素一样，可以在翻译后附着于其他蛋白质，并表征了导致 Smt3p C 末端缀合激活的过程。首先，SMT3 翻译产物被内切蛋白水解以暴露 Gly98（成熟的 C 末端）。Gly98 的存在对于 Smt3p 与蛋白质底物缀合的能力至关重要，并补充 smt3 Delta 菌株的致死性，Smt3p 通过由 Uba2p 组成的新型异二聚酶进行 ATP 依赖性激活， 先前鉴定出与泛素激活酶 (E1s) C 端相似的 71 kDa 蛋白，以及 Aos1p（Smt3p 的激活），这是一种与 E1s N 端相似的 40 kDa 蛋白。条件uba2突变体的实验表明，Uba2p是Smt3p在体内缀合所必需的。此外，UBA2和AOS1都是必需基因，这提供了额外的证据，表明它们在不同的途径中发挥作用，其在细胞活力中的作用是将Smt3p与其他蛋白质缀合。
SMT3 is an essential Saccharomyces cerevisiae gene encoding a 11.5 kDa protein similar to the mammalian ubiquitin-like protein SUMO-1. We have found that Smt3p, like SUMO-1 and ubiquitin, can be attached to other proteins post-translationally and have characterized the processes leading to the activation of the Smt3p C-terminus for conjugation. First, the SMT3 translation product is cleaved endoproteolytically to expose Gly98, the mature C-terminus, The presence of Gly98 is critical for Smt3p's abilities to be conjugated to protein substrates and to complement the lethality of a smt3 Delta strain, Smt3p undergoes ATP-dependent activation by a novel heterodimeric enzyme consisting of Uba2p, a previously identified 71 kDa protein similar to the C-terminus of ubiquitin-activating enzymes (E1s), and Aos1p (activation of Smt3p), a 40 kDa protein similar to the N-terminus of E1s. Experiments with conditional uba2 mutants showed that Uba2p is required for Smt3p conjugation in vivo, Furthermore, UBA2 and AOS1 are both essential genes, providing additional evidence that they act in a distinct pathway whose role in cell viability is to conjugate Smt3p to other proteins.