Hu Min, Gu Lichuan, Li Muyang, Jeffrey Philip D, Gu Wei, Shi Yigong
Department of Molecular Biology, Princeton University, Princeton, New Jersey, USA.
PLoS Biol. 2006 Feb;4(2):e27. doi: 10.1371/journal.pbio.0040027. Epub 2006 Jan 17.
Herpesvirus-associated ubiquitin-specific protease (HAUSP, also known as USP7), a deubiquitylating enzyme of the ubiquitin-specific processing protease family, specifically deubiquitylates both p53 and MDM2, hence playing an important yet enigmatic role in the p53-MDM2 pathway. Here we demonstrate that both p53 and MDM2 specifically recognize the N-terminal tumor necrosis factor-receptor associated factor (TRAF)-like domain of HAUSP in a mutually exclusive manner. HAUSP preferentially forms a stable HAUSP-MDM2 complex even in the presence of excess p53. The HAUSP-binding elements were mapped to a peptide fragment in the carboxy-terminus of p53 and to a short-peptide region preceding the acidic domain of MDM2. The crystal structures of the HAUSP TRAF-like domain in complex with p53 and MDM2 peptides, determined at 2.3-A and 1.7-A resolutions, respectively, reveal that the MDM2 peptide recognizes the same surface groove in HAUSP as that recognized by p53 but mediates more extensive interactions. Structural comparison led to the identification of a consensus peptide-recognition sequence by HAUSP. These results, together with the structure of a combined substrate-binding-and-deubiquitylation domain of HAUSP, provide important insights into regulation of the p53-MDM2 pathway by HAUSP.
疱疹病毒相关泛素特异性蛋白酶（HAUSP，也称为USP7）是泛素特异性加工蛋白酶家族的一种去泛素化酶，它能特异性地去除p53和MDM2的泛素化修饰，因此在p53-MDM2通路中发挥着重要但仍不明朗的作用。在此我们证明，p53和MDM2以互斥的方式特异性识别HAUSP的N端肿瘤坏死因子受体相关因子（TRAF）样结构域。即使在存在过量p53的情况下，HAUSP也优先形成稳定的HAUSP-MDM2复合物。HAUSP结合元件被定位到p53羧基末端的一个肽段以及MDM2酸性结构域之前的一个短肽区域。分别以2.3埃和1.7埃分辨率测定的与p53和MDM2肽段结合的HAUSP TRAF样结构域的晶体结构表明，MDM2肽段识别HAUSP中与p53识别的相同表面凹槽，但介导了更广泛的相互作用。结构比较导致鉴定出HAUSP的一个共有肽段识别序列。这些结果，连同HAUSP的底物结合和去泛素化结构域组合的结构，为HAUSP对p53-MDM2通路的调控提供了重要见解。
