Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 5 de 5
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
J Biochem ; 173(4): 317-326, 2023 Mar 31.
Artigo em Inglês | MEDLINE | ID: mdl-36610722

RESUMO

Pathogenic bacteria deliver virulence factors called effectors into host cells in order to facilitate infection. The Shigella effector proteins IpaH1.4 and IpaH2.5 are members of the 'novel E3 ligase' (NEL)-type bacterial E3 ligase family. These proteins ubiquitinate the linear ubiquitin assembly complex (LUBAC) to inhibit nuclear factor (NF)-κB activation and, concomitantly, the inflammatory response. However, the molecular mechanisms underlying the interaction and recognition between IpaH1.4 and IpaH2.5 and LUBAC are unclear. Here we present the crystal structures of the substrate-recognition domains of IpaH1.4 and IpaH2.5 at resolutions of 1.4 and 3.4 Å, respectively. The LUBAC-binding site on IpaH1.4 was predicted based on structural comparisons with the structures of other NEL-type E3s. Structural and biochemical data were collected and analysed to determine the specific residues of IpaH1.4 that are involved in interactions with LUBAC and influence NF-κB signaling. The new structural insight presented here demonstrates how bacterial pathogens target innate immune signaling pathways.


Assuntos
Shigella , Ubiquitina , Ubiquitina/metabolismo , NF-kappa B/metabolismo , Ubiquitina-Proteína Ligases/genética , Ubiquitina-Proteína Ligases/metabolismo , Transdução de Sinais , Shigella/metabolismo , Ubiquitinação
2.
Nat Cell Biol ; 22(6): 663-673, 2020 06.
Artigo em Inglês | MEDLINE | ID: mdl-32393887

RESUMO

The linear ubiquitin chain assembly complex (LUBAC), which consists of HOIP, SHARPIN and HOIL-1L, promotes NF-κB activation and protects against cell death by generating linear ubiquitin chains. LUBAC contains two RING-IBR-RING (RBR) ubiquitin ligases (E3), and the HOIP RBR is responsible for catalysing linear ubiquitination. We found that HOIL-1L RBR plays a crucial role in regulating LUBAC. HOIL-1L RBR conjugates monoubiquitin onto all LUBAC subunits, followed by HOIP-mediated conjugation of linear chains onto monoubiquitin, and these linear chains attenuate the functions of LUBAC. The introduction of E3-defective HOIL-1L mutants into cells augmented linear ubiquitination, which protected the cells against Salmonella infection and cured dermatitis caused by reduced LUBAC levels due to SHARPIN loss. Our results reveal a regulatory mode of E3 ligases in which the accessory E3 in LUBAC downregulates the main E3 by providing preferred substrates for autolinear ubiquitination. Thus, inhibition of HOIL-1L E3 represents a promising strategy for treating severe infections or immunodeficiency.


Assuntos
Proteínas de Transporte/fisiologia , Morte Celular , Doença Hepática Induzida por Substâncias e Drogas/imunologia , Dermatite de Contato/imunologia , Peptídeos e Proteínas de Sinalização Intracelular/fisiologia , Salmonelose Animal/imunologia , Ubiquitina-Proteína Ligases/fisiologia , Ubiquitina/metabolismo , Animais , Células Cultivadas , Doença Hepática Induzida por Substâncias e Drogas/metabolismo , Doença Hepática Induzida por Substâncias e Drogas/patologia , Dermatite de Contato/metabolismo , Dermatite de Contato/patologia , Embrião de Mamíferos/imunologia , Embrião de Mamíferos/metabolismo , Embrião de Mamíferos/patologia , Fibroblastos/imunologia , Fibroblastos/metabolismo , Fibroblastos/patologia , Regulação da Expressão Gênica , Camundongos Knockout , NF-kappa B/genética , NF-kappa B/metabolismo , Salmonella/patogenicidade , Salmonelose Animal/metabolismo , Salmonelose Animal/patologia , Índice de Gravidade de Doença , Transdução de Sinais , Ubiquitinação
3.
Cells ; 3(3): 848-64, 2014 Aug 18.
Artigo em Inglês | MEDLINE | ID: mdl-25257025

RESUMO

Protein ubiquitination plays indispensable roles in the regulation of cell homeostasis and pathogenesis of neoplastic, infectious, and neurodegenerative diseases. Given the importance of this modification, it is to be expected that several pathogenic bacteria have developed the ability to utilize the host ubiquitin system for their own benefit. Modulation of the host ubiquitin system by bacterial effector proteins inhibits innate immune responses and hijacks central signaling pathways. Bacterial effectors mimic enzymes of the host ubiquitin system, but may or may not be structurally similar to the mammalian enzymes. Other effectors bind and modify components of the host ubiquitin system, and some are themselves subject to ubiquitination. This review will describe recent findings, based on structural analyses, regarding how pathogens use post-translational modifications of proteins to establish an infection.

4.
J Mol Biol ; 425(15): 2623-31, 2013 Aug 09.
Artigo em Inglês | MEDLINE | ID: mdl-23542009

RESUMO

Ubc13 is a ubiquitin-conjugating enzyme that plays a key role in the nuclear factor-κB signal transduction pathway in human diseases. The Shigella flexneri effector OspI affects inflammatory responses by catalyzing the deamidation of a specific glutamine residue at position 100 in Ubc13 during infection. This modification prevents the activation of the TNF (tumor necrosis factor) receptor-associated factor 6, leading to modulation of the diacylglycerol-CBM (CARD-Bcl10-Malt1) complex-TNF receptor-associated factor 6-nuclear factor-κB signaling pathway. To elucidate the structural basis of OspI function, we determined the crystal structures of the catalytically inert OspI C62A mutant and its complex with Ubc13 at resolutions of 3.0 and 2.96Å, respectively. The structure of the OspI-Ubc13 complex revealed that the interacting surfaces between OspI and Ubc13 are a hydrophobic surface and a complementary charged surface. Furthermore, we predict that the complementary charged surface of OspI plays a key role in substrate specificity determination.


Assuntos
Shigella flexneri/química , Shigella flexneri/metabolismo , Enzimas de Conjugação de Ubiquitina/química , Enzimas de Conjugação de Ubiquitina/metabolismo , Fatores de Virulência/química , Fatores de Virulência/metabolismo , Cristalografia por Raios X , Humanos , Modelos Moleculares , Ligação Proteica , Domínios e Motivos de Interação entre Proteínas , Processamento de Proteína Pós-Traducional , Estrutura Quaternária de Proteína , Eletricidade Estática
5.
Artigo em Inglês | MEDLINE | ID: mdl-22691779

RESUMO

The 26S proteasome is an ATP-dependent protease responsible for selective degradation of polyubiquitylated proteins. Recent studies have suggested that proteasome assembly is a highly ordered multi-step process assisted by specific chaperones. Rpn14, an assembly chaperone for ATPase-ring formation, specifically recognizes the ATPase subunit Rpt6. The structure of Rpn14 at 2.0 Šresolution in space group P6(4) has previously been reported, but the detailed mechanism of Rpn14 function remains unclear. Here, a new crystal structure of Rpn14 with an E384A mutation is presented in space group P2(1) at 1.6 Šresolution. This high-resolution structure provides a framework for understanding proteasome assembly.


Assuntos
Proteínas de Transporte/química , Proteínas de Saccharomyces cerevisiae/química , Saccharomyces cerevisiae/química , Sequência de Aminoácidos , Proteínas de Transporte/genética , Ligação de Hidrogênio , Modelos Moleculares , Dados de Sequência Molecular , Mutação , Complexo de Endopeptidases do Proteassoma , Estrutura Quaternária de Proteína , Estrutura Terciária de Proteína , Proteínas de Saccharomyces cerevisiae/genética , Homologia Estrutural de Proteína
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...