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2nbv
From Proteopedia
Solution structure of the Rpn13 Pru domain engaging the hPLIC2 UBL domain
Structural highlights
Disease[UBQL2_HUMAN] Defects in UBQLN2 are the cause of amyotrophic lateral sclerosis type 15 with or without frontotemporal dementia (ALS15) [MIM:300857]. A neurodegenerative disorder affecting upper motor neurons in the brain and lower motor neurons in the brain stem and spinal cord, resulting in fatal paralysis. Sensory abnormalities are absent. The pathologic hallmarks of the disease include pallor of the corticospinal tract due to loss of motor neurons, presence of ubiquitin-positive inclusions within surviving motor neurons, and deposition of pathologic aggregates. The etiology of amyotrophic lateral sclerosis is likely to be multifactorial, involving both genetic and environmental factors. The disease is inherited in 5-10% of the cases. Patients with ALS15 may develop frontotemporal dementia.[1] [2] [3] [4] Function[ADRM1_HUMAN] Functions as a proteasomal ubiquitin receptor. Recruits the deubiquitinating enzyme UCHL5 at the 26S proteasome and promotes its activity.[5] [6] [7] [8] [9] [UBQL2_HUMAN] Increases the half-life of proteins destined to be degraded by the proteasome; may modulate proteasome-mediated protein degradation.[10] Publication Abstract from PubMedThree receptors (Rpn1/S2/PSMD2, Rpn10/S5a, Rpn13/Adrm1) in the proteasome bind substrates by interacting with conjugated ubiquitin chains and/or shuttle factors (Rad23/HR23, Dsk2/PLIC/ubiquilin, Ddi1) that carry ubiquitinated substrates to proteasomes. We solved the structure of two such receptors with their preferred shuttle factor, namely hRpn13Pru:hPLIC2UBL and scRpn1 T1:scRad23UBL. We find that ubiquitin folds in Rad23 and Dsk2 are fine-tuned by residue substitutions to achieve high affinity for Rpn1 and Rpn13, respectively. A single substitution in hPLIC2 yields enhanced interactions with the Rpn13 ubiquitin contact surface and sterically blocks hRpn13 binding to its preferred ubiquitin chain type, K48-linked chains. Rpn1 T1 binds two ubiquitins in tandem and we find that Rad23 binds exclusively to the higher-affinity Helix28/Helix30 site. Rad23 contacts at Helix28/Helix30 are optimized compared to ubiquitin by multiple conservative amino acid substitutions. Thus, shuttle factors deliver substrates to proteasomes through fine-tuned ubiquitin-like surfaces. Structures of Rpn1 T1:Rad23 and hRpn13:hPLIC2 Reveal Distinct Binding Mechanisms between Substrate Receptors and Shuttle Factors of the Proteasome.,Chen X, Randles L, Shi K, Tarasov SG, Aihara H, Walters KJ Structure. 2016 Jul 6. pii: S0969-2126(16)30125-3. doi:, 10.1016/j.str.2016.05.018. PMID:27396824[11] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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