Rewiring of RSK-PDZ Interactome by Linear Motif Phosphorylation

Phosphorylation of short linear peptide motifs is a widespread process for the dynamic regulation of protein–protein interactions. However, the global impact of phosphorylation events on the protein–protein interactome is rarely addressed. The disordered C-terminal tail of ribosomal S6 kinase 1 (RSK1) binds to PDZ domain-containing scaffold proteins, and it harbors a phosphorylatable PDZ binding motif (PBM) responsive to epidermal growth factor (EGF) stimulation. Here, we examined binding of two versions of the RSK1 PBM, either phosphorylated or unphosphorylated at position −3, to almost all (95%) of the 266 PDZ domains of the human proteome. PBM phosphorylation dramatically altered the PDZ domain-binding landscape of RSK1, by strengthening or weakening numerous interactions to various degrees. The RSK-PDZome interactome analyzed in this study reveals how linear motif-based phospho-switches convey stimulus-dependent changes in the context of related network components

Редокс-регуляция динамического характера фенотипа эндотелиоцитов кровеносных сосудов

ЭНДОТЕЛИАЛЬНЫЕ КЛЕТКИКЛЕТКИЭНДОТЕЛИЙКРОВЕНОСНЫЕ СОСУДЫФЕНОТИПГЕНЕТИЧЕСКИЕ ФЕНОМЕНЫОКИСЛИТЕЛЬНО-ВОССТАНОВИТЕЛЬНЫЕ РЕАКЦИИЭНЕРГЕТИЧЕСКИЙ ОБМЕНПЕРЕКИСНОЕ ОКИСЛЕНИЕ ЛИПИДО

Structure of the E6/E6AP/p53 complex required for HPV-mediated degradation of p53

The p53 pro-apoptotic tumor suppressor is mutated or functionally altered in most cancers. In epithelial tumors induced by “high-risk” mucosal Human Papillomaviruses (hrm-HPVs), including human cervical carcinoma and a growing number of head-and-neck cancers (1), p53 is degraded by the viral oncoprotein E6 (2). In this process, E6 binds to a short LxxLL consensus sequence within the cellular ubiquitin ligase E6AP (3). Subsequently, the E6/E6AP heterodimer recruits and degrades p53 (4). Neither E6 nor E6AP are separately able to recruit p53 (3,5), and the precise mode of assembly of E6, E6AP and p53 is unknown. Here, we solved the crystal structure of a ternary complex comprising full-length HPV16 E6, the LxxLL motif of E6AP and the core domain of p53. The LxxLL motif of E6AP renders the conformation of E6 competent for interaction with p53 by structuring a p53-binding cleft on E6. Mutagenesis of critical positions at the E6-p53 interface disrupts p53 degradation. The E6-binding site of p53 is distal from previously described DNA- and protein-binding surfaces of the core domain. This suggests that, in principle, E6 may avoid competition with cellular factors by targeting both free and bound p53 molecules. The E6/E6AP/p53 complex represents a prototype of viral hijacking of both the ubiquitin-mediated protein degradation pathway and the p53 tumor suppressor pathway. The present structure provides a framework for the design of inhibitory therapeutic strategies against HPV-mediated oncogenesis

Production of recombinant E6 protein of HPV type 16 responsible for cervical cancers (identification and characterization of specific interaction between E6 protein and four-way DNA junctions)

STRASBOURG-Sc. et Techniques (674822102) / SudocSudocFranceF

Production, analyse structurale et caractérisation fonctionnelle d'oncoprotéines E6 issues de différents papillomavirus

Autrefois rattachés aux papovaviridae avec les polyomavirus, les papillomavirus sont individualisés depuis peu et forment l unique genre de la famille papillomaviridae. Les papillomavirus (PVs) induisent chez les mammifères et les oiseaux des lésions prolifératives dans les tissus épithéliaux. La plupart de ces lésions sont bénignes (verrues et condylomes) mais elles dégénèrent parfois en cancers. Les papillomavirus humains (HPV) génitaux à haut risque sont responsables de 99% des cas du cancer du col de l utérus, deuxième cause de mortalité chez la femme. Certains HPV cutanés à haut risque provoquent également des cancers de la peau. Les oncoprotéines E6 et E7 sont particulièrement impliquées dans le processus de carcinogenèse, en interagissant notamment avec les protéines anti-tumorales p53 et pRb. Cependant, E6 et E7 lient et souvent provoquent la dégradation d environ 100 autres protéines cellulaires régulant elles-mêmes l expression, la stabilité ou les modifications posttranscriptionnelles d autres protéines. La structure de E6 a longtemps résisté à toute analyse, car la protéine était très difficile à produire par voie recombinante sous une forme repliée. Notre équipe a travaillé sur ce problème depuis 1995. Les travaux que j ai menés durant cette thèse ont permis de compléter l étude structurale et fonctionnelle de la protéine E6 du HPV et d aborder des études comparables pour ses orthologues de différents virus animaux. De telles données constituent un progrès considérable attendu depuis une vingtaine d années. L optimisation des protocoles, l exploration des domaines, la mutagenèse dirigée et la solubilisation des protéines à l aide de leurs ligands, se sont avérés essentiels pour aboutir à l étude structurale. Remarquablement, pour produire et solubiliser des protéines relativement proches, il m'a fallu adopter différentes stratégies. D autre part, la maitrise de la production et de la qualité de ces protéines m'a permis d étudier le rôle biologique de certains phénomènes (dimérisation, liaison à LXXLL ), par une approche de mutagénèse respectueuse du bon repliement des protéines.STRASBOURG-Sc. et Techniques (674822102) / SudocSudocFranceF

Letter to the editor: Strong visible photoluminescence from hollow silica nanoparticles

Starting with crystalline silicon nanoparticles, which were produced by CO2 laser pyrolysis of silane in a gas flow reactor, we have synthesized amorphous silica nanoparticles via oxidation. Upon excitation with UV light, the novel nanostructured material gives rise to an intense red photoluminescence (PL) which resembles that of some silicon nanostructures. Transmission electron microscopy studies and electron energy loss spectroscopy confirm that the nanoparticles are composed of amorphous silica and that the majority of them are hollow. The strong red PL is attributed to defects or molecular species located at the inner and outer surfaces of the hollow nanoparticles. Its similarity to the PL of nanostructured silicon seems fortuitous

Design of a PDZbody, a bivalent binder of the E6 protein from human papillomavirus

Chronic infection by high risk human papillomavirus (HPV) strains may lead to cancer. Expression of the two viral oncoproteins E6 and E7 is largely responsible for immortalization of infected cells. The HPV E6 is a small (approximately 150 residues) two domain protein that interacts with a number of cellular proteins including the ubiquitin ligase E6-associated protein (E6AP) and several PDZ-domain containing proteins. Our aim was to design a high-affinity binder for HPV E6 by linking two of its cellular targets. First, we improved the affinity of the second PDZ domain from SAP97 for the C-terminus of HPV E6 from the high-risk strain HPV18 using phage display. Second, we added a helix from E6AP to the N-terminus of the optimized PDZ variant, creating a chimeric bivalent binder, denoted PDZbody. Full-length HPV E6 proteins are difficult to express and purify. Nevertheless, we could measure the affinity of the PDZbody for E6 from another high-risk strain, HPV16 (K-d = 65 nM). Finally, the PDZbody was used to co-immunoprecipitate E6 protein from HPV18-immortalized HeLa cells, confirming the interaction between PDZbody and HPV18 E6 in a cellular context