Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya 467-8603, Japan; JST, PRESTO, 3-1 Tanabe-dori, Mizuho-ku, Nagoya 467-8603, Japan.
Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya 467-8603, Japan.
FEBS Lett. 2014 Nov 28;588(23):4422-30. doi: 10.1016/j.febslet.2014.10.013. Epub 2014 Oct 19.
Ataxin-3, which is encoded by a gene that has been associated with Machado-Joseph disease, contains a catalytic N-terminal Josephin domain with deubiquitinase activity. Here, we show that the Josephin domain of ataxin 3 catalyzes endo-type cleavage of Lys48-linked polyubiquitin. Furthermore, NMR data obtained following site-specific paramagnetic spin labeling of Lys48-linked di-ubiquitin revealed that both ubiquitin units interact with the Josephin domain, with the C-terminal Gly76 of the proximal unit being situated in the vicinity of the catalytic triad of Josephin domain. Our results help to elucidate how the substrate is recognized by the Josephin domain and properly positioned for an endo-type deubiquitination reaction.
由与 Machado-Joseph 病相关的基因编码的 Ataxin-3 含有具有去泛素化酶活性的催化 N 端 Josephin 结构域。在这里，我们表明 Ataxin 3 的 Josephin 结构域催化 Lys48 连接的聚泛素的内型切割。此外，通过 Lys48 连接的二泛素的定点顺磁自旋标记获得的 NMR 数据表明，两个泛素单位都与 Josephin 结构域相互作用，近端单位的 C 末端 Gly76 位于 Josephin 结构域的催化三联体附近。我们的结果有助于阐明底物如何被 Josephin 结构域识别并正确定位进行内型去泛素化反应。
