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1.
Nucleic Acids Res ; 45(2): 805-817, 2017 01 25.
Artículo en Inglés | MEDLINE | ID: mdl-27903914

RESUMEN

The KEOPS/EKC complex is a tRNA modification complex involved in the biosynthesis of N6-threonylcarbamoyladenosine (t6A), a universally conserved tRNA modification found on ANN-codon recognizing tRNAs. In archaea and eukaryotes, KEOPS is composed of OSGEP/Kae1, PRPK/Bud32, TPRKB/Cgi121 and LAGE3/Pcc1. In fungi, KEOPS contains an additional subunit, Gon7, whose orthologs outside of fungi, if existent, remain unidentified. In addition to displaying defective t6A biosynthesis, Saccharomyces cerevisiae strains harboring KEOPS mutations are compromised for telomere homeostasis, growth and transcriptional co-activation. To identify a Gon7 ortholog in multicellular eukaryotes as well as to uncover KEOPS-interacting proteins that may link t6A biosynthesis to the diverse set of KEOPS mutant phenotypes, we conducted a proteomic analysis of human KEOPS. This work identified 152 protein interactors, one of which, C14ORF142, interacted strongly with all four KEOPS subunits, suggesting that it may be a core component of human KEOPS. Further characterization of C14ORF142 revealed that it shared a number of biophysical and biochemical features with fungal Gon7, suggesting that C14ORF142 is the human ortholog of Gon7. In addition, our proteomic analysis identified specific interactors for different KEOPS subcomplexes, hinting that individual KEOPS subunits may have additional functions outside of t6A biosynthesis.


Asunto(s)
Complejos Multiproteicos , Sistemas de Lectura Abierta , Subunidades de Proteína , Proteómica , Proteínas de Saccharomyces cerevisiae/metabolismo , Secuencia de Aminoácidos , Línea Celular , Humanos , Proteínas Intrínsecamente Desordenadas/metabolismo , Complejos Multiproteicos/química , Mapeo de Interacción de Proteínas , Mapas de Interacción de Proteínas , Proteómica/métodos , Proteínas de Saccharomyces cerevisiae/química
2.
ACS Chem Biol ; 17(4): 941-956, 2022 04 15.
Artículo en Inglés | MEDLINE | ID: mdl-35385646

RESUMEN

Ubiquitin (Ub)-binding domains embedded in intracellular proteins act as readers of the complex Ub code and contribute to regulation of numerous eukaryotic processes. Ub-interacting motifs (UIMs) are short α-helical modular recognition elements whose role in controlling proteostasis and signal transduction has been poorly investigated. Moreover, impaired or aberrant activity of UIM-containing proteins has been implicated in numerous diseases, but targeting modular recognition elements in proteins remains a major challenge. To overcome this limitation, we developed Ub variants (UbVs) that bind to 42 UIMs in the human proteome with high affinity and specificity. Structural analysis of a UbV:UIM complex revealed the molecular determinants of enhanced affinity and specificity. Furthermore, we showed that a UbV targeting a UIM in the cancer-associated Ub-specific protease 28 potently inhibited catalytic activity. Our work demonstrates the versatility of UbVs to target short α-helical Ub receptors with high affinity and specificity. Moreover, the UbVs provide a toolkit to investigate the role of UIMs in regulating and transducing Ub signals and establish a general strategy for the systematic development of probes for Ub-binding domains.


Asunto(s)
Proteínas , Ubiquitina , Humanos , Unión Proteica , Proteínas/metabolismo , Ubiquitina/metabolismo
3.
ACS Chem Biol ; 17(6): 1472-1484, 2022 06 17.
Artículo en Inglés | MEDLINE | ID: mdl-35613471

RESUMEN

A comprehensive analysis of the phosphoproteome is essential for understanding molecular mechanisms of human diseases. However, current tools used to enrich phosphotyrosine (pTyr) are limited in their applicability and scope. Here, we engineered new superbinder Src-Homology 2 (SH2) domains that enrich diverse sets of pTyr-peptides. We used phage display to select a Fes-SH2 domain variant (superFes; sFes1) with high affinity for pTyr and solved its structure bound to a pTyr-peptide. We performed systematic structure-function analyses of the superbinding mechanisms of sFes1 and superSrc-SH2 (sSrc1), another SH2 superbinder. We grafted the superbinder motifs from sFes1 and sSrc1 into 17 additional SH2 domains and confirmed increased binding affinity for specific pTyr-peptides. Using mass spectrometry (MS), we demonstrated that SH2 superbinders have distinct specificity profiles and superior capabilities to enrich pTyr-peptides. Finally, using combinations of SH2 superbinders as affinity purification (AP) tools we showed that unique subsets of pTyr-peptides can be enriched with unparalleled depth and coverage.


Asunto(s)
Proteoma , Dominios Homologos src , Humanos , Espectrometría de Masas , Fosfotirosina/análisis , Fosfotirosina/química , Fosfotirosina/metabolismo , Unión Proteica , Proteoma/metabolismo
4.
Sci Rep ; 9(1): 4119, 2019 03 11.
Artículo en Inglés | MEDLINE | ID: mdl-30858488

RESUMEN

USP37 is a deubiquitinase (DUB) with roles in the regulation of DNA damage repair and the cohesion of sister chromatids during mitosis. USP37 contains a unique insert of three ubiquitin interacting motifs (UIMs) within its catalytic DUB domain. We investigated the role of the three UIMs in the ability of USP37 to cleave di-ubiquitin chains. We found that the third UIM of USP37 recognizes the proximal ubiquitin moiety of K48 di-Ub to potentiate cleavage activity and posit that this mechanism of action may be generalizable to other chain types. In the case of K48-linked ubiquitin chains this potentiation stemmed largely from a dramatic increase in catalytic rate (kcat). We also developed and characterized three ubiquitin variant (UbV) inhibitors that selectively engage distinct binding sites in USP37. In addition to validating the deduced functional roles of the three UIMs in catalysis, the UbVs highlight a novel and effective means to selectively inhibit members of the difficult to drug DUB family.


Asunto(s)
Dominio Catalítico , Endopeptidasas/química , Animales , Endopeptidasas/genética , Endopeptidasas/metabolismo , Humanos , Mutación , Unión Proteica , Ubiquitinas/química , Ubiquitinas/metabolismo , Pez Cebra
5.
Protein Sci ; 28(5): 848-856, 2019 05.
Artículo en Inglés | MEDLINE | ID: mdl-30793400

RESUMEN

We previously described structural and functional characterization of the first ubiquitin variant (UbV), UbV.v27.1, engineered by phage display to bind with high affinity to a specific ubiquitin interacting motif (UIM). We identified two substitutions relative to ubiquitin (Gly10Val/His68Tyr) that were critical for enhancing binding affinity but could only rationalize the mechanism of action of the Tyr68 substitution. Here, we extend our characterization and uncover the mechanism by which the Val10 substitution enhances binding affinity. We show that Val10 in UbV.v27.1 drives UbV dimerization through an intermolecular ß-strand exchange. Dimerization serves to increase the contact surface between the UIM and UbV and also affords direct contacts between two UIMs through an overall 2:2 binding stoichiometry. Our identification of the role of Val10 in UbV dimerization suggests a general means for the development of dimeric UbVs with improved affinity and specificity relative to their monomeric UbV counterparts. Statement: Previously, we used phage display to engineer a UbV that bound tightly and specifically to a UIM. Here, we discovered that tight binding is partly due to the dimerization of the UbV, which increases the contact surface between the UbV and UIM. We show that UbV dimerization is dependent on the Gly10Val substitution, and posit that dimerization may provide a general means for engineering UbVs with improved binding properties.


Asunto(s)
Ubiquitina/química , Ubiquitina/genética , Valina/genética , Sustitución de Aminoácidos , Sitios de Unión , Técnicas de Visualización de Superficie Celular , Humanos , Modelos Moleculares , Unión Proteica , Ingeniería de Proteínas , Multimerización de Proteína , Estructura Secundaria de Proteína
6.
Structure ; 27(6): 1000-1012.e6, 2019 06 04.
Artículo en Inglés | MEDLINE | ID: mdl-31056421

RESUMEN

Pseudoenzymes have been identified across a diverse range of enzyme classes and fulfill important cellular functions. Examples of pseudoenzymes exist within ubiquitin conjugating and deubiquitinase (DUB) protein families. Here we characterize FAM105A/OTULINL, the only putative pseudodeubiquitinase of the ovarian tumor protease (OTU domain) family in humans. The crystal structure of FAM105A revealed that the OTU domain possesses structural deficiencies in both active site and substrate-binding infrastructure predicted to impair normal DUB function. We confirmed the absence of catalytic function against all ubiquitin linkages and an inability of FAM105A to bind ubiquitin compared with catalytically active FAM105B/OTULIN. FAM105A co-localized with KDEL markers and Lamin B1 at the endoplasmic reticulum (ER) and nuclear envelope, respectively. Accordingly, the FAM105A interactome exhibited significant enrichment in proteins localized to the ER/outer nuclear, Golgi and vesicular membranes. In light of undetectable deubiquitinase activity, we posit that FAM105A/OTULINL functions through its ability to mediate protein-protein interactions.


Asunto(s)
Enzimas Desubicuitinizantes/química , Endopeptidasas/química , Retículo Endoplásmico/metabolismo , Membranas Intracelulares/metabolismo , Secuencia de Aminoácidos , Animales , Dominio Catalítico , Línea Celular Tumoral , Cristalografía por Rayos X , Enzimas Desubicuitinizantes/genética , Enzimas Desubicuitinizantes/metabolismo , Endopeptidasas/genética , Endopeptidasas/metabolismo , Células HEK293 , Humanos , Ratones , Modelos Moleculares , Unión Proteica , Dominios Proteicos , Homología de Secuencia de Aminoácido , Ubiquitina/química , Ubiquitina/metabolismo , Enzimas Ubiquitina-Conjugadoras/química , Enzimas Ubiquitina-Conjugadoras/genética , Enzimas Ubiquitina-Conjugadoras/metabolismo
7.
J Mol Biol ; 431(6): 1160-1171, 2019 03 15.
Artículo en Inglés | MEDLINE | ID: mdl-30763569

RESUMEN

We applied a yeast-two-hybrid (Y2H) analysis to screen for ubiquitin variant (UbV) inhibitors of a human deubiquitinase (DUB), ubiquitin-specific protease 2 (USP2). The Y2H screen used USP2 as the bait and a prey library consisting of UbVs randomized at four specific positions, which were known to interact with USP2 from phage display analysis. The screen yielded numerous UbVs that bound to USP2 both as a Y2H interaction in vivo and as purified proteins in vitro. The Y2H-derived UbVs inhibited the catalytic activity of USP2 in vitro with nanomolar-range potencies, and they bound and inhibited USP2 in human cells. Mutational and structural analysis showed that potent and selective inhibition could be achieved by just two substitutions in a UbV, which exhibited improved hydrophobic and hydrophilic contacts compared to the wild-type ubiquitin interaction with USP2. Our results establish Y2H as an effective platform for the development of UbV inhibitors of DUBs in vivo, providing an alternative strategy for the analysis of DUBs that are recalcitrant to phage display and other in vitro methods.


Asunto(s)
Enzimas Desubicuitinizantes/metabolismo , Ubiquitina Tiolesterasa/metabolismo , Ubiquitina/metabolismo , Enzimas Desubicuitinizantes/antagonistas & inhibidores , Células HEK293 , Humanos , Modelos Moleculares , Complejo de la Endopetidasa Proteasomal/metabolismo , Unión Proteica , Técnicas del Sistema de Dos Híbridos , Ubiquitina Tiolesterasa/antagonistas & inhibidores
8.
Structure ; 26(9): 1226-1236.e3, 2018 09 04.
Artículo en Inglés | MEDLINE | ID: mdl-30033217

RESUMEN

Skp1-Cul1-F-box (SCF) E3 ligases constitute the largest and best-characterized family of the multisubunit E3 ligases with important cellular functions and numerous disease links. The specificity of an SCF E3 ligase is established by one of the 69 human F-box proteins that are recruited to Cul1 through the Skp1 adaptor. We previously reported generation of ubiquitin variants (UbVs) targeting Fbw7 and Fbw11, which inhibit ligase activity by binding at the F-box-Skp1 interface to competitively displace Cul1. In the present study, we employed an optimized engineering strategy to generate specific binding UbVs against 17 additional Skp1-F-box complexes. We validated our design strategy and uncovered the structural basis of binding specificity by crystallographic analyses of representative UbVs bound to Skp1-Fbl10 and Skp1-Fbl11. Our study highlights the power of combining phage display with structure-based design to develop UbVs targeting specific protein surfaces.


Asunto(s)
Proteínas Ligasas SKP Cullina F-box/química , Proteínas Ligasas SKP Cullina F-box/metabolismo , Ubiquitinas/química , Ubiquitinas/farmacología , Sitios de Unión , Técnicas de Visualización de Superficie Celular , Cristalografía por Rayos X , Proteínas Cullin/metabolismo , Inhibidores Enzimáticos/química , Inhibidores Enzimáticos/farmacología , Proteínas F-Box/metabolismo , Femenino , Células HEK293 , Humanos , Histona Demetilasas con Dominio de Jumonji/metabolismo , Modelos Moleculares , Unión Proteica , Proteínas Ligasas SKP Cullina F-box/antagonistas & inhibidores , Bibliotecas de Moléculas Pequeñas/química , Bibliotecas de Moléculas Pequeñas/farmacología , Relación Estructura-Actividad
9.
Protein Sci ; 26(5): 1060-1069, 2017 05.
Artículo en Inglés | MEDLINE | ID: mdl-28276594

RESUMEN

Ubiquitin interacting motifs (UIMs) are short α-helices found in a number of eukaryotic proteins. UIMs interact weakly but specifically with ubiquitin conjugated to other proteins, and in so doing, mediate specific cellular signals. Here we used phage display to generate ubiquitin variants (UbVs) targeting the N-terminal UIM of the yeast Vps27 protein. Selections yielded UbV.v27.1, which recognized the cognate UIM with high specificity relative to other yeast UIMs and bound with an affinity more than two orders of magnitude higher than that of ubiquitin. Structural and mutational studies of the UbV.v27.1-UIM complex revealed the molecular details for the enhanced affinity and specificity of UbV.v27.1, and underscored the importance of changes at the binding interface as well as at positions that do not contact the UIM. Our study highlights the power of the phage display approach for selecting UbVs with unprecedented affinity and high selectivity for particular α-helical UIM domains within proteomes, and it establishes a general approach for the development of inhibitors targeting interactions of this type.


Asunto(s)
Complejos de Clasificación Endosomal Requeridos para el Transporte/química , Biblioteca de Péptidos , Ingeniería de Proteínas , Proteínas de Saccharomyces cerevisiae/química , Saccharomyces cerevisiae/química , Ubiquitina/química , Secuencias de Aminoácidos , Complejos de Clasificación Endosomal Requeridos para el Transporte/genética , Dominios Proteicos , Estructura Cuaternaria de Proteína , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/genética , Ubiquitina/genética
10.
Nat Commun ; 4: 1983, 2013.
Artículo en Inglés | MEDLINE | ID: mdl-23770917

RESUMEN

Mutations in the park2 gene, encoding the RING-inBetweenRING-RING E3 ubiquitin ligase parkin, cause 50% of autosomal recessive juvenile Parkinsonism cases. More than 70 known pathogenic mutations occur throughout parkin, many of which cluster in the inhibitory amino-terminal ubiquitin-like domain, and the carboxy-terminal RING2 domain that is indispensable for ubiquitin transfer. A structural rationale showing how autosomal recessive juvenile Parkinsonism mutations alter parkin function is still lacking. Here we show that the structure of parkin RING2 is distinct from canonical RING E3 ligases and lacks key elements required for E2-conjugating enzyme recruitment. Several pathogenic mutations in RING2 alter the environment of a single surface-exposed catalytic cysteine to inhibit ubiquitination. Native parkin adopts a globular inhibited conformation in solution facilitated by the association of the ubiquitin-like domain with the RING-inBetweenRING-RING C-terminus. Autosomal recessive juvenile Parkinsonism mutations disrupt this conformation. Finally, parkin autoubiquitinates only in cis, providing a molecular explanation for the recessive nature of autosomal recessive juvenile Parkinsonism.


Asunto(s)
Genes Recesivos/genética , Enfermedad de Parkinson/genética , Ubiquitina-Proteína Ligasas/genética , Secuencia de Aminoácidos , Animales , Biocatálisis , Drosophila melanogaster , Humanos , Modelos Moleculares , Datos de Secuencia Molecular , Mutación/genética , Unión Proteica , Estructura Terciaria de Proteína , Alineación de Secuencia , Especificidad por Sustrato , Enzimas Ubiquitina-Conjugadoras/metabolismo , Ubiquitina-Proteína Ligasas/química
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