NMR resonance assignments of the NZF domain of mouse HOIL-1L free and bound to linear di-ubiquitin.

Nuclear factor-κB (NF-κB) activation plays a central role in immunity and inflammation. In the canonical NF-κB activation pathway, linear polyubiquitin chains conjugated by the linear ubiquitin chain assembly complex (LUBAC) are specifically recognized by the Npl4 zinc finger (NZF) domain of heme-oxidized IRP2 ligase-1L (HOIL-1L). Recently, a crystal structure of the NZF domain in complex with linear di-ubiquitin has been reported; however, to understand the recognition mechanism in more detail, it is also necessary to investigate the structure and dynamics of the NZF domain in solution. In this study, we report the 1 H, 13 C, and 15 N backbone and side chain resonance assignments of the NZF domain in the free form as well as the backbone resonance assignments of the NZF domain in the di-ubiquitin-bound form. Based on the assigned chemical shifts, we analyzed the secondary structure propensity, suggesting that the free form of the NZF domain forms secondary structure elements as observed in the di-ubiquitin-bound form. We expect that our data will provide an important basis for characterization of the free NZF domain and elucidation of the detailed recognition mechanism in solution.