PDF(Pubmed)
Abstract：
Small ubiquitin-binding domains (UBDs) recognize small surface patches on ubiquitin with weak affinity, and it remains a conundrum how specific cellular responses may be achieved. Npl4-type zinc-finger (NZF) domains are ∼30 amino acid, compact UBDs that can provide two ubiquitin-binding interfaces, imposing linkage specificity to explain signaling outcomes. We here comprehensively characterize the linkage preference of human NZF domains. TAB2 prefers Lys6 and Lys63 linkages phosphorylated on Ser65, explaining why TAB2 recognizes depolarized mitochondria. Surprisingly, most NZF domains do not display chain linkage preference, despite conserved, secondary interaction surfaces. This suggests that some NZF domains may specifically bind ubiquitinated substrates by simultaneously recognizing substrate and an attached ubiquitin. We show biochemically and structurally that the NZF1 domain of the E3 ligase HOIPbinds preferentially to site-specifically ubiquitinated forms of NEMO and optineurin. Thus, despite their small size, UBDs may impose signaling specificity via multivalent interactions with ubiquitinated substrates.
摘要：
小泛素结合域（UBD）识别泛素上的小表面斑块，亲和力弱，如何实现特定的细胞反应仍然是一个难题。Npl4型锌指(NZF)结构域为~30个氨基酸，可以提供两个泛素结合接口的紧凑型UBD，施加连锁特异性来解释信号传导结果。我们在这里全面表征了人类NZF结构域的连锁偏好。TAB2更喜欢在Ser65上磷酸化的Lys6和Lys63连接，这解释了为什么TAB2识别去极化的线粒体。令人惊讶的是,大多数NZF域不显示链链接偏好，尽管保守，次级相互作用表面。这表明一些NZF结构域可以通过同时识别底物和附着的泛素来特异性结合泛素化底物。我们在生物化学和结构上表明，E3连接酶HOIP的NZF1结构域优先与NEMO和视神经磷酸酶的位点特异性泛素化形式结合。因此，尽管尺寸很小，UBD可以通过与泛素化底物的多价相互作用来施加信号传导特异性。
