Internally Tagged Ubiquitin: a Tool to Identify Linear Polyubiquitin-modified Proteins by Mass Spectrometry
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Even though ubiquitination controls a plethora of cellular processes, modifications by linear polyubiquitin have so far only been linked with acquired and innate immunity, lymphocyte development and genotoxic stress response. Until now, a single E3 ligase complex (LUBAC), one specific deubiquitinase (OTULIN) and a very few substrates have been identified. The existing methods for the study of lysine-based polyubiquitination are not suitable for the detection of linear polyubiquitin-modified proteins. Here, we present a novel approach to discovering linear polyubiquitin-modified substrates by combining lysine-less internally tagged ubiquitin (INT-Ub.7KR) with SILAC-based mass spectrometry. We applied our approach in TNFα-stimulated T-REx HEK293T cells and afterwards validated newly identified linear polyubiquitin targets. Moreover, we demonstrated that linear polyubiquitination of the novel LUBAC substrate TRAF6 is essential for the NFκB signalling. Overall, we have established a powerful method for the detection of linear polyubiquitin substrates.
AuthorsKliza, K; Taumer, C; Pinzuti, I; Franz-Wachtel, M; Kunzelmann, S; STIEGLITZ, B; Macek, B; Husnjak, K
- College Publications