Tsg101/ESCRT-I recruitment regulated by the dual binding modes of K63-linked diubiquitin

HECT domain interaction with ubiquitin binding sites on Tsg101-UEV controls HIV-1 egress, maturation, and infectivity

“…As noted above, our structural studies employing the HECT domain of Nedd4-1 identified the UEV β-hairpin and vestigial active site as the primary regions in contact with the HECT domain. As previously reported, these regions of the UEV bind mono-Ub and K63-linked Ub noncovalently ( 24 , 25 ). Previous studies showed that certain isolated HECT domains capable of synthesizing K63-linked Ub chains promoted WT-level rescue when fused to the residual C2 domain of Nedd4-2s, while others did not.…”

“…The UEV domain of Tsg101 resembles canonical E2 Ub-conjugating enzymes but is unable to catalyze Ub transfer because it lacks the active site cysteine that forms the transient thioester bond with the C terminus of Ub ( 26 , 27 ). Moreover, it binds Ub but at novel sites that are not fully equivalent to that in canonical E2s ( 24 , 25 , 28 ). Still, given the similarities, we initially probed for evidence of a direct interaction between the Nedd4-1 HECT domain and the Tsg101 UEV domain at three sites ( Fig.…”

“…The UEV regions in proximity to the HECT lie on the β-hairpin and in proximity to the vestigial active site. These regions bind Ub noncovalently ( 24 , 25 ). As noted above, on the front surface of the HECT, regions in proximity to the UEV lie in the interlobe region near the canonical E2 binding site and noncovalent Ub exosite, and on the reverse surface, the UEV was found to associate with the α1-helix region.…”

STING signalling is terminated through ESCRT-dependent microautophagy of vesicles originating from recycling endosomes

“…We further provided evidence that polyubiquitin of STING interacted with Tsg101 through its UEV domain, which may lead to the recruitment of other ESCRT proteins to complete lysosomal microautophagy. Of note, the very recent nuclear magnetic resonance result supported the direct binding of Tsg101 with K63-linked ubiquitin 38 .…”

Structural Dynamics of E6AP E3 Ligase HECT Domain and Involvement of a Flexible Hinge Loop in the Ubiquitin Chain Synthesis Mechanism

“…6−8 It is known that Ub 2 is involved in the regulation of various cellular processes. 6,7 For instance, binding of unanchored liner Ub 2 chains to the NF-κB essential modulator (NEMO) is required for NF-κB activation by TNFα and other agonists. 6 To elucidate the structural dynamics of the HECT domain of E6AP, here we used high-speed atomic force microscopy (HS-AFM).…”