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Structural analysis of the CSN complex to understand its inhibition mechanism

ABSTRACT: We performed interaction and structural analyses to unravel the molecular mechanisms underlying CSN inhibition. Various methods including Cryo-EM, cross-linking mass spectrometry, quantitative mass spectrometry and biochemical assays have been employed to define inhibitor-induced interaction and structural changes of the CSN complex in vitro and in cells.

INSTRUMENT(S):

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Embryonic Stem Cell

SUBMITTER: Fenglong Jiao

LAB HEAD: Lan Huang

PROVIDER: PXD063786 | Pride | 2025-11-20

REPOSITORIES: Pride

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			Action	DRS
	OrbitrapLUMOS_20241216_06.raw	Raw
	OrbitrapLUMOS_20241216_07.raw	Raw
	OrbitrapLUMOS_20241223_01.raw	Raw
	OrbitrapLUMOS_20241223_02.raw	Raw
	OrbitrapLUMOS_20241223_03.raw	Raw

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Integrative Structural Characterization of the Human Canonical and Non-canonical Cop9 Signalosome Complexes

Project description:The COP9 signalosome (CSN) is an evolutionarily conserved protein complex that functions as a deneddylase to inactivate Cullin-RING E3 ligases for controlling protein ubiquitination. CSN possesses structural flexibility that is important for its activation upon binding to a diverse array of CRLs. The canonical and non-canonical CSN complexes consist of 8 (CSN1-8) and 9 (CSN1-9) subunits, respectively. Although CSN9 is not essential for CSN assembly and function, it appears to be important in non-catalytic regulation of CRLs by CSN. Here we employed a combinatory cross-linking mass spectrometry (XL-MS) approach to generate the largest PPI maps of human CSN complexes, which significantly enhanced the precision of integrative structural modeling. The resulting integrative structures allowed us not only to elucidate architectures of both complexes, but also to assess CSN structural dynamics that was not described in the crystal structure. In addition, we have determined CSN9 docking sites and its impact on the CSN structure. While CSN9 binding did not induce global conformational changes, it triggered subunit local reorientations that may be associated with CSN9 involvement in CSN-mediated steric regulation of CRLs.

2020-02-04 | PXD014673 | Pride

XL-MS and Native MS for CSN-CRL2 complexes

Project description:Cullin-Ring E3 Ligases (CRLs) regulate a multitude of cellular pathways through specific substrate receptors. The COP9 signalosome (CSN) deactivates CRLs by removing NEDD8 (N8) from activated Cullins. The structure of stable CSN-CRL can be used to understand this mechanism of regulation. Here we present the first structures of the neddylated and deneddylated CSN-CRL2 complexes by combining single particle cryo-electron microscopy (cryo-EM) with chemical cross-linking mass spectrometry (MS). These structures reveal a conserved mechanism of CSN activation, consisting of conformational clamping of the CRL2 substrate by CSN2/CSN4, release of the catalytic CSN5/CSN6 heterodimer and finally activation of the CSN5 deneddylation machinery. Using hydrogen deuterium exchange-MS we show that CRL2 binding and conformational activation of CSN5/CSN6 occur in a neddylation-independent manner. The presence of NEDD8 is required to activate the CSN5 active site. Overall, by synergising cryo-EM with MS, we identified novel sensory regions of the CSN that mediate its stepwise activation mechanism and provide a framework for better understanding the regulatory mechanism of other Cullin family members.

2019-09-13 | PXD013018 | Pride

RNA sequencing of corticospinal neurons and control callosal projection neurons purified from the cerebral cortex of adult wild-type and Sod1G86R mice, a model of amyotrophic lateral sclerosis, at four disease-relevant ages.

Project description:Amyotrophic Lateral Sclerosis is clinically defined as the combined degeneration of the corticospinal and corticobulbar neurons (CSN) along with the bulbar and spinal motor neurons (SMN). While a growing body of evidence points to the motor cortex, where CSN are located, as the potential initiation site of ALS, little is known about how CSN degenerate. To gain insights into the molecular mechanisms behind CSN selective degeneration, we first developed an approach to purify this neuronal population from the cerebral cortex of adult wild-type and Sod1G86R mice, combining retrograde labelling and Fluorescence Activated Cell Sorting. In parallel, a second population of cortical neurons, the callosal projection neurons (CPN) located in the layers II/III of the cerebral cortex were also purified. CPN and CSN are both cortical excitatory projection neurons but as opposed to CSN, CPN do not degenerate in Sod1G86R mice, and served as control population. CSN and CPN were purified from same animals, at two presymptomatic ages (3 and 60 days) and two symptomatic ages, 90 and 105 days. A total of 57 samples were further processed and analysed (CSN: 30d: n=4 WT and 3 Sod1G86R; 60d: n=4 WT and 4 Sod1G86R; 90d: n=4 WT and 4 Sod1G86R; 105d: n=4 WT and 2 Sod1G86R; CPN: 30d: n=4 WT and 3 Sod1G86R; 60d: n=2 WT and 3 Sod1G86R; 90d: n=4 WT and 4 Sod1G86R; 105d: n=4 WT and 4 Sod1G86R).

2020-12-30 | E-MTAB-7876 | biostudies-arrayexpress

Fungal COP9 signalosome assembly requires connection of two trimeric intermediates for integration of intrinsic deneddylase

Project description:The eight-subunit COP9 signalosome (CSN complex), controls the exchange of E3 ubiquitin cullin RING ligase receptors through its deneddylase activity, providing specificity to eukaryotic protein degradation. The conserved eight-subunit CSN complex is required for multicellular development of the filamentous fungus Aspergillus nidulans. The human, as well as the fungal CSN complex assembles through a heptameric subcomplex (pre-CSN complex) that is activated by the integration of the eighth subunit, the catalytic CsnE/5 deneddylase. The focus of this work was to unveil the assembly of the native fungal pre-CSN complex via combined genetic and biochemical approaches. Interactomes of various functional GFP-Csn subunit fusions, produced in pre-CSN deficient fungal double csn subunit gene deletion strains, were compared by affinity purifications coupled to mass spectrometry analyses. With this approach, two distinct heterotrimeric CSN subcomplexes were identified as pre-CSN assembly intermediates, namely CsnA/1-C/3-H/8 and CsnD/4-F/6-G/7 that form independently of CsnB/2 that connects the heterotrimers to a heptameric subcomplex and enables subsequent integration of CsnE/5, yielding in the enzymatically active CSN holocomplex. Surveillance mechanisms control accurate Csn subunit abundances and correct cellular localization for sequential assembly, since deprivation of Csn subunits change the abundance and location of the remaining Csn subunits.

2023-08-10 | PXD043205 | Pride

Structural analysis of the CSN complex to understand its inhibition mechanism

Project description:We performed interaction and structural analyses to unravel the molecular mechanisms underlying CSN inhibition. Various methods including Cryo-EM, quantitative mass spectrometry and biochemical assays have been employed to define inhibitor-induced interaction and structural changes of the CSN complex in vitro and in cells.

2025-11-22 | PXD063822 | Pride

A proteomics approach reveals digestive and nutritional responses to food intake in anadromous Coilia nasus

Project description:The estuarine tapertail anchovy, Coilia nasus, is an anadromous fish that undertakes over a 600-km spawning migration along the Yangtze River of China. They generally cease feeding during this process, but we recently documented that a small proportion of them appear to feed. Research on proteomic responses is essential for understanding the phenomenon of C. nasus feeding. In this study, we used an iTRAQ-based proteomics approach to study the changes in protein expression in response to food intake in C. nasus following voluntary fasting. Coilia nasus in the feeding group (CSI) were fed shrimp or small fish, whereas those in the control group (CSN) were starved. We identified 3279 proteins in the gastric tissue/stomach, of which 279 were significantly differentially expressed. In all, 133 differentially expressed proteins (DEPs) were upregulated and 146 proteins were downregulated in CSI compared with those in CSN C. nasus. In addition to gastric acid secretion caused by gastric distention, a functional analysis suggested that a series of DEPs were involved mainly in the regulation of protein digestion (e.g., carboxypeptidase A1 and chymotrypsin A-like), immune response (e.g., lysozyme and alpha 2-macroglobulin), and nutrition metabolism (e.g., glyceraldehyde 3-phosphate dehydrogenase, glycogenin, long-chain acyl-CoA synthetase, and creatine kinase). Real-time PCR confirmed that the mRNA levels of the DEPs were similar those obtained using iTRAQ. These results indicate that the nutrients obtained through food were effectively utilized by C. nasus, thereby providing energy for swimming, gonadal maturation, primary metabolism, and an enhanced immune function to better resist pathogen interference. This research contributes to the elucidation of nutritional regulation mechanisms of C. nasus to better protect the wild population.

2022-05-25 | PXD033476 | Pride

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Project description:Objective: HIV-1 Nef suppresses immune surveillance mechanisms to promote viral pathogenesis. Cellular receptor CD4 is essential for HIV entry into host cells, though becomes problematic at later stages in the virus replication cycle. CD4 at the plasma membrane is targeted by Nef for endocytosis and lysosomal degradation via recruitment of clathrin adaptor complex 2 (AP2 complex). Our goal is to use cross-linking mass spectrometry and integrative modeling to aid in structure determination of flexible portions of the Nef-CD4-AP2 complex. Methods: We use disuccinimidyl sulfoxide (DSSO), a MS-cleavable, bifunctional amine-reactive small molecule, to cross-link proximal Lys residues or N-termini of a purified reconstituted Nef-CD4 C-terminal domain fusion protein bound to the AP2Δμ2-CTD complex. Cross-linked proteins were separated by SDS-PAGE, excised from the gel and digested with trypsin. The resulting peptides were analyzed by specialized LC-MS3 experiments for identification of cross-linked residues using MSconvert (to obtain individual MS2 and MS3 level mgf files), ProteinProspector (to obtain peptide identification results files), and XLTools (to identify cross-linked peptides from results, MS2, and MS3 files). Additional scripts were used to summarize cross-linked results. Results: We find that an intricate combination of conformational changes occurs in both Nef and AP2 to enable CD4 binding and downregulation. A pocket on Nef previously identified as crucial for recruiting class I MHC is also responsible for recruiting CD4, revealing a potential approach to inhibit two of Nef’s activities and sensitize the virus to immune clearance.

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2023-10-04 | PXD035589 | Pride

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2021-05-07 | PXD022690 | Pride

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