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Cryo-EM structure of P97-VCPIP1 complex
Structural highlights
DiseaseTERA_HUMAN Defects in VCP are the cause of inclusion body myopathy with early-onset Paget disease and frontotemporal dementia (IBMPFD) [MIM:167320; also known as muscular dystrophy, limb-girdle, with Paget disease of bone or pagetoid amyotrophic lateral sclerosis or pagetoid neuroskeletal syndrome or lower motor neuron degeneration with Paget-like bone disease. IBMPFD features adult-onset proximal and distal muscle weakness (clinically resembling limb girdle muscular dystrophy), early-onset Paget disease of bone in most cases and premature frontotemporal dementia.[1] [2] [3] [4] [5] Defects in VCP are the cause of amyotrophic lateral sclerosis type 14 with or without frontotemporal dementia (ALS14) [MIM:613954. ALS14 is 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 ALS14 may develop frontotemporal dementia.[6] FunctionTERA_HUMAN Necessary for the fragmentation of Golgi stacks during mitosis and for their reassembly after mitosis. Involved in the formation of the transitional endoplasmic reticulum (tER). The transfer of membranes from the endoplasmic reticulum to the Golgi apparatus occurs via 50-70 nm transition vesicles which derive from part-rough, part-smooth transitional elements of the endoplasmic reticulum (tER). Vesicle budding from the tER is an ATP-dependent process. The ternary complex containing UFD1L, VCP and NPLOC4 binds ubiquitinated proteins and is necessary for the export of misfolded proteins from the ER to the cytoplasm, where they are degraded by the proteasome. The NPLOC4-UFD1L-VCP complex regulates spindle disassembly at the end of mitosis and is necessary for the formation of a closed nuclear envelope. Regulates E3 ubiquitin-protein ligase activity of RNF19A (By similarity). Component of the VCP/p97-AMFR/gp78 complex that participates in the final step of the sterol-mediated ubiquitination and endoplasmic reticulum-associated degradation (ERAD) of HMGCR. Also involved in DNA damage response: recruited to double-strand breaks (DSBs) sites in a RNF8- and RNF168-dependent manner and promotes the recruitment of TP53BP1 at DNA damage sites. Recruited to stalled replication forks by SPRTN: may act by mediating extraction of DNA polymerase eta (POLH) to prevent excessive translesion DNA synthesis and limit the incidence of mutations induced by DNA damage.[7] [8] [9] [10] [11] [12] [13] Publication Abstract from PubMedThe VCPIP1-P97/VCP (Valosin-Containing Protein) complex is required for post-mitotic Golgi cisternae reassembly and maintenance in interphase. However, the organization and mechanism of this complex in regulating Golgi membrane fusion is still elusive. Here, the cryo-electron microscopy (cryo-EM) structures of the human VCPIP1-P97/VCP complex are presented. These studies reveal that three independent VCPIP1 molecules sit over the C-terminal substrate exit tunnel formed by P97/VCP homo-hexamer, resulting in an unusual C3 to C6 symmetric barrel architecture. The UFD1 (unknown function domain 1) from VCPIP1, but not the N-terminal OTU domain and the C-terminal UBL domain, docks to the two adjacent D2 domains of P97/VCP, allosterically causing the cofactors binding domain-NTDs (N-terminal domains) of P97/VCP in a "UP" and D1 domain in an ATPase competent conformation. Conversely, VCPIP1 bound P97/VCP hexamer favors the binding of P47, and thus the intact SNARE complex, promoting Golgi membrane fusion. These studies not only reveal the unexpected organization of humanVCPIP1-P97/VCP complex, but also provide new insights into the mechanism of VCPIP1-P97/VCP mediated Golgi apparatus reassembly, which is a fundamental cellular event for protein and lipid processing. Molecular Basis of VCPIP1 and P97/VCP Interaction Reveals Its Functions in Post-Mitotic Golgi Reassembly.,Liao T, Li R, Lu P, Liu Y, Yang R, Guo H, Wu Z, Wang R, Yuan L, Hu Z, Gao H, Li F Adv Sci (Weinh). 2024 Sep 5:e2403417. doi: 10.1002/advs.202403417. PMID:39234822[14] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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