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| 14. |
- Anandapadamanaban, Madhanagopal, et al.
(författare)
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E3 ubiquitin-protein ligase TRIM21-mediated lysine capture by UBE2E1 reveals substrate-targeting mode of a ubiquitin-conjugating E2
- 2019
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Ingår i: Journal of Biological Chemistry. - : American Society for Biochemistry and Molecular Biology. - 0021-9258 .- 1083-351X. ; 294:30, s. 11404-11419
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Tidskriftsartikel (refereegranskat)abstract
- The E3 ubiquitin-protein ligase TRIM21, of the RING-containing tripartite motif (TRIM) protein family, is a major autoantigen in autoimmune diseases and a modulator of innate immune signaling. Together with ubiquitin-conjugating enzyme E2 E1 (UBE2E1), TRIM21 acts both as an E3 ligase and as a substrate in autoubiquitination. We here report a 2.82-angstrom crystal structure of the human TRIM21 RING domain in complex with the human E2-conjugating UBE2E1 enzyme, in which a ubiquitin-targeted TRIM21 substrate lysine was captured in the UBE2E1 active site. The structure revealed that the direction of lysine entry is similar to that described for human proliferating cell nuclear antigen (PCNA), a small ubiquitin-like modifier (SUMO)-targeted substrate, and thus differs from the canonical SUMO-targeted substrate entry. In agreement, we found that critical UBE2E1 residues involved in the capture of the TRIM21 substrate lysine are conserved in ubiquitin-conjugating E2s, whereas residues critical for SUMOylation are not conserved. We noted that coordination of the acceptor lysine leads to remodeling of amino acid side-chain interactions between the UBE2E1 active site and the E2-E3 direct interface, including the so-called linchpin residue conserved in RING E3s and required for ubiquitination. The findings of our work support the notion that substrate lysine activation of an E2-E3-connecting allosteric path may trigger catalytic activity and contribute to the understanding of specific lysine targeting by ubiquitin-conjugating E2s.
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| 15. |
- Anandapadamanaban, Madhanagopal
(författare)
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Structural insights into protein-protein interactions governing regulation in transcription initiation and ubiquitination
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Virtually every aspect of the cellular processes in eukaryotes requires that the interactions between protein molecules are well coordinated in different regulatory pathways. Any protein dysfunction involved in these regulatory pathways might lead to various pathological conditions. Understanding the structural and functional peculiarities of these proteins molecular machineries will help in formulating structure-based drug design.The first regulatory process studied here is the RNA polymerase-II mediated transcription of the eukaryotic protein-coding genes to produce mRNAs. This process requires the formation of the ‘transcription initiation’ by the assembly of Pre-Initiation Complex (PIC) formation at a core promoter region. Regulation at this initiation level is a key mechanism for the control of gene expression that governs cellular growth and differentiation. The transcription Factor IID (TFIID) is a conserved multiprotein general transcription factor with an essential role in nucleating the PIC formation, composed of TATA Binding Protein (TBP) and about 14 TBP Associated Factors (TAFs). The here presented crystal structure (1.97Å) of TBP bound to TAND1 and TAND2 domains from TAF1 reveals a detailed molecular pattern of interactions involving both transcriptionally activating and repressing regions in TBP, thereby uncovering central principles for anchoring of TBP-binding motifs. Together with NMR and cellular analysis, this work provides the structural basis of competitive binding with TFIIA to modulate TBP in promoter recognition.In eukaryotes, another fundamental mechanism in the regulation of cellular physiology is the posttranslational modification of substrate proteins by ubiquitin, termed ‘ubiquitination’. Important actors in this mechanism are the ubiquitin-ligases (E3s) that culminate the transfer of ubiquitin to the substrate and govern the specificity of this system. One E3 ligase in particular, TRIM21, defines a subgroup of the Tripartite Motif (TRIM) family, which belongs to the major RING-type of E3 ubiquitin ligases, and plays an important role in pathogenesis of autoimmunity by mediating ubiquitination of transcription factors. The crystal structure (2.86Å) of the RING domain from TRIM21 in complex with UBE2E1, an E2 conjugating enzyme, together with the NMR and SAXS analysis as well as biochemical functional analysis, reveals the molecular basis for the dynamic binding interfaces. The TRIM21 mode of ubiquitin recognition and activation for catalytic transfer of ubiquitin can be modeled onto the entire TRIM family.Finally, we explored the concepts of conformational selection in proteins as a possible key component for protein-mediated transcriptional regulation. In this framework, MexR, a bacterial repressor of the MexAB-OprM efflux pump, and its mutant Arg21Trp were studied as an example for proteins presenting different conformations. The residue Arg21Trp mutation is clinically identified to cause of Multi-Drug Resistant (MDR) by attenuated DNA binding, and leads to the overexpression of the MexAB-OprM efflux pump. With the crystal structure (2.19Å) of MexR mutant Arg21Trp, in combination with MD-simulations and SAXS for both wild-type and mutant, we could unravel the atomic details of the wild-type conformations consisting in subsets of populations of DNA bound and unbound forms. Remarkably, the mutant Arg21Trp stabilize the DNA unbound state and shifts MexR in a pre-existing equilibrium, from a repressed to a derepressed state.Taken together, these studies substantially broaden our knowledge at a molecular level in protein interactions that are involved in transcriptional regulation and ubiquitination, studied by a carefully selected combination of complementary structural methods spanning different resolutions and time scales.
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| 16. |
- Anandapadamanaban, Madhanagopal, et al.
(författare)
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Structure of a TRIM21 - UBE2El complex reveals the specificity of E2 and ubiquitin recognition by TRIM E3 RINGs
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- TRIM21, a RlNG-containing E3 ubiquitin-ligase of the TRIM protein family, is a major autoantigen in SLE and Sjögren's syndrome as well as a modifier of interferon regulatory factors, thereby regulating innate immune signalling. We herein report the 2.86 Å crystal structure ofhuman TRIM211-91 comprising the RING domain (residues 16-55), in complex with the human E2 conjugating UBE2El enzyme (also denoted UbcH6). The crystal structure, joint with analysis by NMR and SAXS as well as structure-directed mutations and functional assays provides a detailed view of the specificity-determining contacts that support specific E2 recognition in the TRIM family. A detailed comparison of our structure with known E2 bound ubiquitin complexes, supported by biochemical analyses, reveals the molecular basis for TRIM21 interactions with donor ubiquitin that activates catalytic ubiquitin transfer. Finally, our structure convincingly demonstrates the placement of the Ub-targeted Lys61 of the adjacent TRIM211- 91 close to the catalytically active UBE2El cysteine, and how the Lys61 amide is activated fora nucleophilic attack by hydrogen-bondeffected deshielding by conserved acidic residues at the E2 active site. In all, our structural findings provide molecular details ofthe selectivity involved in TRIM21 interactions with its cognate UBE2E1 enzyme and how TRIM21 positions ubiquitin in a catalytic conformation for ubiquitin transfer, and presents a snapshot of the Ub ligation step on a specific target residue of TRIM211-91 as an auto-ubiquitinated pseudo-substrate at high concentration. Increased structural and functional understanding of the TRIM mediated ubiquitination will aid development ofnovel therapeutic approaches in the entire TRIM family ofproteins.
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| 17. |
- Appel, Silke, et al.
(författare)
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Potential association of muscarinic receptor 3 gene variants with primary Sjogren's syndrome
- 2011
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Ingår i: Annals of the Rheumatic Diseases. - : BMJ. - 0003-4967 .- 1468-2060. ; 70:7, s. 1327-1329
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Tidskriftsartikel (refereegranskat)abstract
- Background: Primary Sjögren's syndrome (pSS) is characterised by a chronic inflammation of exocrine glands. Salivary gland infiltrates, however, do not correlate well with disease symptoms, and a primary role for the salivary gland parenchyma in disease development has been suggested. Specifically, dysfunction of exocrine pathways involving the muscarinic receptor 3 (CHRM3) has been indicated. Objective: To investigate possible genetic divergence in the CHRM3 gene in patients with pSS. Methods: 530 patients with pSS and 532 controls from a combined Swedish and Norwegian cohort were genotyped for 84 single nucleotide polymorphisms (SNPs) distributed throughout CHRM3. Results: Genetic association was observed with five SNPs localised in intron 3 and 4 of CHRM3, the strongest being rs7548522 (minor allele frequency = 0.06, OR=1.93, 95% CI (1.24 to 3.01); p=0.0033). In addition, clinical parameters, including focus score, abnormal Schirmer's test and presence of autoantibodies, were associated with different SNPs in CHRM3. Conclusion: The study demonstrates a novel association of CHRM3 polymorphisms with pSS, suggesting a functional role for CHRM3 and the salivary gland parenchyma in the pathogenesis of pSS.
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| 20. |
- Björk, Albin, et al.
(författare)
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Protein and DNA methylation-based scores as surrogate markers for interferon system activation in patients with primary Sjögren's syndrome
- 2020
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Ingår i: RMD Open. - : BMJ PUBLISHING GROUP. - 2056-5933. ; 6:1
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Standard assessment of interferon (IFN) system activity in systemic rheumatic diseases depends on the availability of RNA samples. In this study, we describe and evaluate alternative methods using plasma, serum and DNA samples, exemplified in the IFN-driven disease primary Sjogren's syndrome (pSS).Methods: Patients with pSS seropositive or negative for anti-SSA/SSB and controls were included. Protein-based IFN (pIFN) scores were calculated from levels of PD-1, CXCL9 and CXCL10. DNA methylation-based (DNAm) IFN scores were calculated from DNAm levels at RSAD2, IFIT1 and IFI44L. Scores were compared with mRNA-based IFN scores measured by quantitative PCR (qPCR), Nanostring or RNA sequencing (RNAseq).Results: mRNA-based IFN scores displayed strong correlations between B cells and monocytes (r=0.93 and 0.95, p<0.0001) and between qPCR and Nanostring measurements (r=0.92 and 0.92, p<0.0001). The pIFN score in plasma and serum was higher in patients compared with controls (p<0.0001) and correlated well with mRNA-based IFN scores (r=0.62-0.79, p<0.0001), as well as with each other (r=0.94, p<0.0001). Concordance of classification as 'high' or 'low' IFN signature between the pIFN score and mRNA-based IFN scores ranged from 79.5% to 88.6%, and the pIFN score was effective at classifying patients and controls (area under the curve, AUC=0.89-0.93, p<0.0001). The DNAm IFN score showed strong correlation to the RNAseq IFN score (r=0.84, p<0.0001) and performed well in classifying patients and controls (AUC=0.96, p<0.0001).Conclusions: We describe novel methods of assessing IFN system activity in plasma, serum or DNA samples, which may prove particularly valuable in studies where RNA samples are not available.
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