Tah1 helix-swap dimerization prevents mixed Hsp90 co-chaperone complexes

Specific co-chaperone adaptors facilitate the recruitment of client proteins to the Hsp90 system. Tah1 binds the C-terminal conserved MEEVD motif of Hsp90, thus linking an eclectic set of client proteins to the R2TP complex for their assembly and regulation by Hsp90. Rather than the normal complement of seven α-helices seen in other tetratricopeptide repeat (TPR) domains, Tah1 unusually consists of the first five only. Consequently, the methionine of the MEEVD peptide remains exposed to solvent when bound by Tah1. In solution Tah1 appears to be predominantly monomeric, and recent structures have failed to explain how Tah1 appears to prevent the formation of mixed TPR domain-containing complexes such as Cpr6-(Hsp90)2-Tah1. To understand this further, the crystal structure of Tah1 in complex with the MEEVD peptide of Hsp90 was determined, which shows a helix swap involving the fifth α-helix between two adjacently bound Tah1 molecules. Dimerization of Tah1 restores the normal binding environment of the bound Hsp90 methionine residue by reconstituting a TPR binding site similar to that in seven-helix-containing TPR domain proteins. Dimerization also explains how other monomeric TPR-domain proteins are excluded from forming inappropriate mixed co-chaperone complexes

Prospero's books or wich english, whose english?

What model of English should we teach? In this paper, I take up the challenge to teachers posed by recent corpus linguists, according to which we now know what real spoken and written English looks like, so what excuse is there for not teaching real English?Now we can have access to much more reliable information and learners will be able to produce with confidence much more idiomatic English, with less effort involved’ (Sinclair, 1987, p. 159). Why should we still insist on teaching made-up textbook sentences and ‘concocted dialogues’ (Carter and McCarthy, 1995, p. 154) when we have, at our fingertips, infinite examples of the ‘real thing?’ (see also Rinvolucri, 1997; Hill, 1999). On the face of it, there would seem to be no argument: why should any teacher of English as a Foreign Language, willfully ignore the evidence for ‘real English’? As T. S. Eliot might have said, had he known about corpus linguistics, ‘after such knowledge what forgiveness’? However, language description and language pedagogy are not the same thing. To understand the challenge of ‘naturally-occurring’ English, we need to broaden the perspective to look beyond the language model itself to the uses to which language forms are put. I will, therefore, examine the pedagogic implications of naturally-occurring English against the background of (1) English as a global language, (2) language as a social act, (3) the recent history of ELT. Having sketched out this background, I will then (4) draw on my own research with students and teachers to outline the possible problems which the implementation of a corpus-based lexical approach may entail and (5) propose a methodological framework which may help to reconcile some of the contradictions identified in the earlier sections of the paper.¿Qué tipo de inglés deberíamos enseñar? En este artículo, recojo el reto lanzado a los profesores por los más recientes lingüistas, en el sentido de que si ya somos conscientes de cómo es el inglés que se habla y se escribe realmente, ¿qué excusa hay para no enseñarlo? Ahora podemos tener acceso a una información mucho más fiable y los estudiantes serán capaces de utilizar una mayor cantidad de modismos en inglés, con mayor confianza y menor esfuerzo (Sinclair, 1987, p. 159). ¿Por ¡qué seguir insistiendo en enseñarles frases estereotipadas y diálogos prefabricados (Carter and McCarthy, 1995, p. 154), cuando tenemos a nuestro alcance infinitos ejemplos reales? (ver también Rinvolucri, 1997; Hill, 1999). Parece que no debería existir ninguna polémica al respecto. ¿Por qué habría de ignorar deliberadamente cualquier profesor de inglés la evidencia del inglés cotidiano? Como T. S. Elliot habría dicho a la vista del corpus lingüístico, “a sabiendas no hay perdón”. Sin embargo, la descripción de una lengua y su metodología no son la misma cosa. Para comprender el desafío del inglés espontáneo, es necesario ampliar la perspectiva e ir más allá del modelo lingüístico a los usos a los que las formas lingüísticas están sujetas. Habrá que cotejar por consiguiente las implicaciones pedagógicas con el peso especifico de (1) el inglés como lengua global, (2) el lenguaje como acto social, (3) la historia reciente de ELT. Una vez esbozado el planteamiento, pasaré a (4) describir mi propia investigación con alumnos y profesores para perfilar los posibles problemas que la puesta en práctica de un enfoque basado en un corpus léxico puede implicar, y (5) proponer un esquema metodológico que pueda ayudar a reconciliar algunas de las contradicciones identificadas antes.Quel genre d’anglais devrions-nous enseigner? Dans cet article, je relève le défi jeté aux professeurs par les linguistes les plus récents, dans le sens que si nous sommes déjà conscients de comment est l’anglais que l’on parle etque l’on écrit réellement, quelle excuse existe pour ne pas l’enseigner? Puisque nous pouvons avoir accès maintenant à une information plus fiable et que les étudiants seront capables de se servir d’une plus grande quantité de modismes en anglais, de s’en servir avec une plus grande confiance et un effort moindre (Sinclair, 1987, 159), a quoi bon continuer à leur apprendre des phrases stéréotypeés et des dialogues préfabriqués (Carter & McCarthy, 1995, 154), quand nous avons à notre portée d’innombrables exemples réels? (voir aussi Rinvolucri, 1997; Hill, 1999). Il paraît qu’il ne devrait pas y avoir aucune polémique à cet égard. Pourquoi n’importe quel professeur d’anglais devrait ignorer délibérement l’évidence de l’anglais quotidien? Comme T. S. Eliot aurait dit en présence du corpus linguistique: “à bon scient, il n’y a pas d’excuse.” Toutefois, la description d’une langue et sa méthodologie ne sont pas la même chose. Pour comprendre le défi de l’anglais spontané, il faut élargir la perspective et aller au-delà du modèle linguistique, aux emplois auxquels sont soumises les formes linguistiques. Il faudra comparer, donc, les implications pédagogiques avec le poids spécifique de (1) l’anglais en tant que langue globale, (2) le langage en tant que acte social, (3) l’histoire récente de ELT. Le projet esquissé, je passerai à décrire (4) ma recherche personnelle avec des élèves et des professeurs afin de profiler les problèmes probables que la mise en oeuvre d’une optique basée sur un corpus lexique peut comporter, et (5) proposer un schéma méthodologique pouvant aider à réconcilier certaines contradictions identifiées avant

Co-crystalization and in vitro biological characterization of 5-Aryl-4-(5-substituted-2-4-dihydroxyphenyl)-1,2,3-thiadiazole Hsp90 inhibitors

A potential therapeutic strategy for targeting cancer that has gained much interest is the inhibition of the ATP binding and ATPase activity of the molecular chaperone Hsp90. We have determined the structure of the human Hsp90α N-terminal domain in complex with a series of 5-aryl-4-(5-substituted-2-4-dihydroxyphenyl)-1,2,3-thiadiazoles. The structures provide the molecular details for the activity of these inhibitors. One of these inhibitors, ICPD 34, causes a structural change that affects a mobile loop, which adopts a conformation similar to that seen in complexes with ADP, rather than the conformation generally seen with the pyrazole/isoxazole-resorcinol class of inhibitors. Competitive binding to the Hsp90 N-terminal domain was observed in a biochemical assay, and these compounds showed antiproliferative activity and induced apoptosis in the HCT116 human colon cancer cell line. These inhibitors also caused induction of the heat shock response with the upregulation of Hsp72 and Hsp27 protein expression and the depletion of Hsp90 clients, CRAF, ERBB2 and CDK4, thus confirming that antiproliferative activity was through the inhibition of Hsp90. The presence of increased levels of the cleavage product of PARP indicated apoptosis in response to Hsp90 inhibitors. This work provides a framework for the further optimization of thiadiazole inhibitors of Hsp90. Importantly, we demonstrate that the thiadiazole inhibitors display a more limited core set of interactions relative to the clinical trial candidate NVP-AUY922, and consequently may be less susceptible to resistance derived through mutations in Hsp9

Hadamard matrices and 1-factorizations of complete graphs

We discuss 1-factorizations of complete graphs that “match” a given Hadamard matrix. We prove the existence of these factorizations for two families of Hadamard matrices: Walsh matrices and certain Paley matrices

Identification of the N-terminal Peptide Binding Site of Glucose-regulated Protein 94

Because the stress protein GRP94 can augment presentation of peptides to T cells, it is important to define how it, as well as all other HSP90 family members, binds peptides. Having previously shown that the N-terminal half of GRP94 can account for the peptide binding activity of the full-length protein, we now locate this binding site by testing predictions of a molecular docking model. The best predicted site was on the opposite face of the β sheet from the pan-HSP90 radicicol-binding pocket, in close proximity to a deep hydrophobic pocket. The peptide and radicicol-binding sites are distinct, as shown by the ability of a radicicol-refractive mutant to bind peptide. When the fluorophore acrylodan is attached to Cys(117)within the hydrophobic pocket, its fluorescence is reduced upon peptide binding, consistent with proximity of the two ligands. Substitution of His(125), which contacts the bound peptide, compromises peptide-binding activity. We conclude that peptide binds to the concave face of the β sheet of the N-terminal domain, where binding is regulated during the action cycle of the chaperone

Expressed in the yeast Saccharomyces cerevisiae, human ERK5 is a client of the Hsp90 chaperone that complements loss of the Slt2p (Mpk1p) cell integrity stress-activated protein kinase

ERK5 is a mitogen-activated protein (MAP) kinase regulated in human cells by diverse mitogens and stresses but also suspected of mediating the effects of a number of oncogenes. Its expression in the slt2Delta Saccharomyces cerevisiae mutant rescued several of the phenotypes caused by the lack of Slt2p (Mpk1p) cell integrity MAP kinase. ERK5 is able to provide this cell integrity MAP kinase function in yeast, as it is activated by the cell integrity signaling cascade that normally activates Slt2p and, in its active form, able to stimulate at least one key Slt2p target (Rlm1p, the major transcriptional regulator of cell wall genes). In vitro ERK5 kinase activity was abolished by Hsp90 inhibition. ERK5 activity in vivo was also lost in a strain that expresses a mutant Hsp90 chaperone. Therefore, human ERK5 expressed in yeast is an Hsp90 client, despite the widely held belief that the protein kinases of the MAP kinase class are non-Hsp90-dependent activities. Two-hybrid and protein binding studies revealed that strong association of Hsp90 with ERK5 requires the dual phosphorylation of the TEY motif in the MAP kinase activation loop. These phosphorylations, at positions adjacent to the Hsp90-binding surface recently identified for a number of protein kinases, may cause a localized rearrangement of this MAP kinase region that leads to creation of the Hsp90-binding surface. Complementation of the slt2Delta yeast defect by ERK5 expression establishes a new tool with which to screen for novel agonists and antagonists of ERK5 signaling as well as for isolating mutant forms of ERK5

Public perception of sustainable energy innovation: A case study from Tilos, Greece

Renewable and smart grid technologies play a key role in delivering a sustainable energy future for non-interconnected islands. In this context, societal acceptance of proposed interventions manifests itself as a major determinant of planned transitions. With extant scholarship on public acceptability of sustainable energy technologies focusing on local opposition to wind farms, this paper presents timely survey data from the island of Tilos to provide a better understanding of energy-users’ perceptions vis-à-vis novel smart island proposals. Against stultifying narratives highlighting the lack of community acceptance for local interventions, we uncover: a) the widespread acceptance of sustainable and smart energy solutions, and b) the willingness of a large proportion of locals to play their part, as engaged energy prosumers, in a green energy transition. In turn, these findings form the basis for future academic and technical interventions on the island, and inform broader conclusions on public engagement around energy

Structure of the TPR Domain of AIP: Lack of Client Protein Interaction with the C-Terminal alpha-7 Helix of the TPR Domain of AIP Is Sufficient for Pituitary Adenoma Predisposition

PMCID: PMC3534021This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited

Multi-chaperone function modulation and association with cytoskeletal proteins are key features of the function of AIP in the pituitary gland

Despite the well-recognized role of loss-of-function mutations of the aryl hydrocarbon receptor interacting protein gene (AIP) predisposing to pituitary adenomas, the pituitary-speci c function of this tumor suppressor remains an enigma. To determine the repertoire of interacting partners for the AIP protein in somatotroph cells, wild-type and variant AIP proteins were used for pull-down/quantitative mass spectrometry experiments against lysates of rat somatotropinoma-derived cells; relevant ndings were validated by co-immunoprecipitation and co-localization. Global gene expression was studied in AIP mutation positive and negative pituitary adenomas via RNA microarrays. Direct interaction with AIP was con rmed for three known and six novel partner proteins. Novel interactions with HSPA5 and HSPA9, together with known interactions with HSP90AA1, HSP90AB1 and HSPA8, indicate that the function/ stability of multiple chaperone client proteins could be perturbed by a de cient AIP co-chaperone function. Interactions with TUBB, TUBB2A, NME1 and SOD1 were also identi ed. The AIP variants p.R304* and p.R304Q showed impaired interactions with HSPA8, HSP90AB1, NME1 and SOD1; p.R304* also displayed reduced binding to TUBB and TUBB2A, and AIP-mutated tumors showed reduced TUBB2A expression. Our ndings suggest that cytoskeletal organization, cell motility/adhesion, as well as oxidative stress responses, are functions that are likely to be involved in the tumor suppressor activity of AIP

Dihydropyridines allosterically modulate Hsp90 providing a novel mechanism for heat shock protein co-induction and neuroprotection

Chaperones play a pivotal role in protein homeostasis, but with age their ability to clear aggregated and damaged protein from cells declines. Tau pathology is a driver of a variety of neurodegenerative disease and in Alzheimer's disease (AD) it appears to be precipitated by the formation of amyloid-β (Aβ) aggregates. Aβ-peptide appears to trigger Tau hyperphosphorylation, formation of neurofibrillary tangles and neurotoxicity. Recently, dihydropyridine derivatives were shown to upregulate the heat shock response (HSR) and provide a neuroprotective effect in an APPxPS1 AD mouse model. The HSR response was only seen in diseased cells and consequently these compounds were defined as co-inducers since they upregulate chaperones and co-chaperones only when a pathological state is present. We show for compounds tested herein, that they target predominantly the C-terminal domain of Hsp90, but show some requirement for its middle-domain, and that binding stimulates the chaperones ATPase activity. We identify the site for LA1011 binding and confirm its identification by mutagenesis. We conclude, that binding compromises Hsp90's ability to chaperone, by modulating its ATPase activity, which consequently induces the HSR in diseased cells. Collectively, this represents the mechanism by which the normalization of neurofibrillary tangles, preservation of neurons, reduced tau pathology, reduced amyloid plaque, and increased dendritic spine density in the APPxPS1 Alzheimer's mouse model is initiated. Such dihydropyridine derivatives therefore represent potential pharmaceutical candidates for the therapy of neurodegenerative disease, such as AD