Regulation of RNF144A E3 Ubiquitin Ligase Activity by Self-association through Its Transmembrane Domain

Abstract

Background: RNF144A is a membrane-associated E3 ubiquitin ligase. Results: The GXXXG motif within the TM domain of RNF144A mediates its self-association and activation of E3 ligase activity. Conclusion: The TM domain regulates RNF144A through two independent steps: membrane localization and GXXXG motifmediated self-association. Significance: The GXXXG motif is conserved among all RBR-TM proteins, suggesting a similar regulation for other RBR-TM proteins.

RING-Between-RING E3 Ligases: Emerging Themes amid the Variations

“…Furthermore, early biochemical studies of Parkin uncovered a mode of auto-inhibition [37]. Subsequently, several other human RBR E3s were shown to be auto-inhibited, though through different mechanisms [23, 35, 36, 38, 39]. Each RBR E3 has its own set of protein targets and each RBR E3 dictates the type of modification (mono-, linear, or poly-ubiquitin chains) that it generates on its targets.…”

“…Removal of specific domains enhances ubiquitination activity of these enzymes, indicative of an auto-inhibitory mechanism [35–37]. Additional biochemical evidence now supports auto-inhibition of HHARI, TRIAD1, and RNF144A, suggesting that auto-inhibition is a common feature among RBR E3s [23, 35, 36, 39, 47]. Therefore, the activity and biochemical study of RBR E3s requires a method to release the auto-inhibition.…”

“…1) and C-terminal transmembrane domain (TMD) so it cannot be auto-inhibited by an intramolecular mechanism analogous to other RBR E3s. Instead, RNF144A ligase activity appears to be modulated by dimerization through its TMD via a specific motif (G-x-x-x-G) [39]. RNF144A, RNF19A, RNF19B, and RNF217 all have predicted TMDs that contain the proposed dimerization motif, suggesting that dimerization via transmembrane domains may emerge as another self-regulatory mechanism of RBR E3s [39].…”

“…Instead, RNF144A ligase activity appears to be modulated by dimerization through its TMD via a specific motif (G-x-x-x-G) [39]. RNF144A, RNF19A, RNF19B, and RNF217 all have predicted TMDs that contain the proposed dimerization motif, suggesting that dimerization via transmembrane domains may emerge as another self-regulatory mechanism of RBR E3s [39]. Interestingly, Parkin self-association has recently been suggested to be important for its ligase activity [50].…”

RNF144A shapes the hierarchy of cytokine signaling to provide protective immunity against influenza

“…RBR proteins are highly conserved through evolution and members of this family, such as Parkin, HHARI and LUBAC are associated with neurological disorders, malignant transformation and/or autoimmunity, respectively [21][22][23][24] . RNF144A is a member of the RBR family that has recently been shown to assemble ubiquitin linkages at the K6-, K11-and K48-positions of ubiquitin in vitro 25 , and whose ubiquitin ligase activity is regulated by self-association through its transmembrane domain 26 . RNF144A plays a role in DNA repair in cancer by targeting DNA-dependent protein kinase (DNA-PK) 27 and PARP1 28 for degradation.…”