1,354,202 research outputs found
SycE allows secretion of YopE-DHFR hybrids by the Yersinia enterocolitica type III Ysc system
No full textThe Ysc type III secretion system allows Yersinia enterocolitica to translocate virulence proteins, called Yop effectors, into the cytosol of eukaryotic cells. Some of the Yop effectors possess an individual chaperone called a Syc protein. The first 15 amino acids of the YopE effector constitute a secretion signal that is sufficient to promote secretion of several reporter proteins. Residues 15-50 of YopE comprise the minimal binding domain for the SycE chaperone. In this study, we investigated the secretion by the Ysc system of several YopE-DHFR hybrid proteins with different folding properties, and evaluated the role of SycE, the cognate chaperone of YopE, in this context. We have analysed the secretion of hybrids containing 16 (YopE16), 52 (YopE52) and 80 (the complete region covered by the chaperone, YopE80) amino acids of YopE or full-length YopE (YopEFL) with wild-type DHFR and two mutants with altered folding properties. The hybrids containing DHFR delta77, the mutant whose folding properties are the most drastically affected, could be secreted in all the conditions tested, even in the absence of the chaperone SycE. In contrast, DHFRwt could only be secreted fused to the first 52 amino acids of YopE, and its secretion was strictly dependent on SycE. The hybrids YopE80-DHFRwt and YopEFL-DHFRwt were not secreted. YopEFL-DHFRwt completely jammed the channel in an SycE-dependent fashion. Our experiments indicate that, in order to be secreted, proteins must be unfolded or only partially folded, and that TSS chaperones could keep their substrates in a secretion-competent conformation, probably by preventing their folding. In addition, they show that the secretion apparatus can reject folded proteins if they are not deeply engaged into the injectisome
Competition between the Yops of Yersinia enterocolitica for delivery into eukaryotic cells : role of the SycE chaperone binding domain of YopE
No full textA type III secretion-translocation system allows Yersinia adhering at the surface of animal cells to deliver a cocktail of effector Yops (YopH, -O, -P, -E, -M, and -T) into the cytosol of these cells. Residues or codons 1 to 77 contain all the information required for the complete delivery of YopE into the target cell (release from the bacterium and translocation across the eukaryotic cell membrane). Residues or codons 1 to 15 are sufficient for release from the wild-type bacterium under Ca(2+)-chelating conditions but not for delivery into target cells. Residues 15 to 50 comprise the binding domain for SycE, a chaperone specific for YopE that is necessary for release and translocation of full-length YopE. To understand the role of this chaperone, we studied the delivery of YopE-Cya reporter proteins and YopE deletants by polymutant Yersinia devoid of most of the Yop effectors (delta HOPEM and delta THE strains). We first tested YopE-Cya hybrid proteins and YopE proteins deleted of the SycE-binding site. In contrast to wild-type strains, these mutants delivered YopE(15)-Cya as efficiently as YopE(130)-Cya. They were also able to deliver YopE(delta 17-77). SycE was dispensable for these deliveries. These results show that residues or codons 1 to 15 are sufficient for delivery into eukaryotic cells and that there is no specific translocation signal in Yops. However, the fact that the SycE-binding site and SycE were necessary for delivery of YopE by wild-type Yersinia suggests that they could introduce hierarchy among the effectors to be delivered. We then tested a YopE-Cya hybrid and YopE proteins deleted of amino acids 2 to 15 but containing the SycE-binding domain. These constructs were neither released in vitro upon Ca(2+) chelation nor delivered into cells by wild-type or polymutant bacteria, casting doubts on the hypothesis that SycE could be a secretion pilot. Finally, it appeared that residues 50 to 77 are inhibitory to YopE release and that binding of SycE overcomes this inhibitory effect. Removal of this domain allowed in vitro release and delivery in cells in the absence as well as in the presence of SycE
Interaction of the Disordered Yersinia Effector Protein YopE with Its Cognate Chaperone SycE
No full textWe describe an efficient approach to model the binding interaction of the disordered effector protein to its cognate chaperone in the type III secretion system (T3SS). Starting from de novo models, we generated ensembles of unfolded conformations of the Yersinia effector YopE using REMD simulations and docked them to the chaperone SycE using a multistep protein docking strategy. The predicted YopE/SycE complex was in good agreement with the experimental structure. The ability of our computational protocol to mimic the structural transition upon chaperone binding opens up the possibility of studying the underlying specificity of chaperone/effector interactions and devising strategies for interfering with T3SS transport
SyCE: An integrated environment for system design in SystemC
No full textWe present an integrated system design environment for SystemC, called SyCE. The system consists of several components for efficient analysis, verification and debugging of SystemC designs. The core tools are 1) ParSyC, a parser for SystemC designs that has also some synthesis options, 2) CheckSyC, a verification tool for formal equivalence checking, property checking and generating checkers for simulation or synthesis, 3) DeSyC, a tool for automatic debugging and error location in netlists, and 4) ViSyC, a visualization tool for schematic and source code view supporting crossprobing and annotation of simulation and debugging results. The tools fully support hierarchy and interact tightly. Designs can be described at different levels of abstraction. 1
Competition between the Yops of Yersinia enterocolitica for delivery into eukaryotic cells: Role of the SycE chaperone binding domain of YopE
No full textA type III secretion-translocation system allows Yersinia adhering at the surface of animal cells to deliver a cocktail of effector Yops (YopH, -O, -P, -E, -M, and -T) into the cytosol of these cells. Residues or codons 1 to 77 contain all the information required for the complete delivery of YopE into the target cell (release from the bacterium and translocation across the eukaryotic cell membrane). Residues or codons 1 to 15 are sufficient for release from the wild-type bacterium under Ca2+-chelating conditions but not for delivery into target cells. Residues 15 to 50 comprise the binding domain for SycE, a chaperone specific for YopE that is necessary for release and translocation of full-length YopE. To understand the role of this chaperone, we studied the delivery of YopE-Cya reporter proteins and YopE deletants by polymutant Yersinia devoid of most of the Yop effectors ([delta]HOPEM and [delta]THE strains). We first tested YopE-Cya hybrid proteins and YopE proteins deleted of the SycE-binding site. In contrast to wild-type strains, these mutants delivered YopE15-Cya as efficiently as YopE130-Cya. They were also able to deliver YopE [delta]17-77. SycE was dispensable for these deliveries. These results show that residues or codons 1 to 15 are sufficient for delivery into eukaryotic cells and that there is no specific translocation signal in Yops. However, the fact that the SycE-binding site and SycE were necessary for delivery of YopE by wild-type Yersinia suggests that they could introduce hierarchy among the effectors to be delivered. We then tested a YopE-Cya hybrid and YopE proteins deleted of amino acids 2 to 15 but containing the SycE-binding domain. These constructs were neither released in vitro upon Ca2+ chelation nor delivered into cells by wild-type or polymutant bacteria, casting doubts on the hypothesis that SycE could be a secretion pilot. Finally, it appeared that residues 50 to 77 are inhibitory to YopE release and that binding of SycE overcomes this inhibitory effect. Removal of this domain allowed in vitro release and delivery in cells in the absence as well as in the presence of SycE.H. and A. Brenninkmeijer ICP fellowship
EU TMR Programme Research Network contract FMRX-CT98-0164
Belgian Fonds National de la Recherche Scientifique Medicale
(Convention 3.4595.97)
Direction generale de la Recherche Scientifique-Communaute Francaise de Belgique
(Action de Recherche Concertee 94/99-172)
Interuniversity Poles of Attraction Program-Belgian State, Prime Minister's Office,
Federal Office for Scientific, Technical and Cultural affairs (PAI 4/03).peer-reviewe
Competition between the Yops of Yersinia enterocolitica for delivery into eukaryotic cells: Role of the SycE chaperone binding domain of YopE
No full textA type III secretion-translocation system allows Yersinia adhering at the surface of animal cells to deliver a cocktail of effector Yops (YopH, -O, -P, -E, -M, and -T) into the cytosol of these cells. Residues or codons 1 to 77 contain all the information required for the complete delivery of YopE into the target cell (release from the bacterium and translocation across the eukaryotic cell membrane). Residues or codons 1 to 15 are sufficient for release from the wild-type bacterium under Ca2+-chelating conditions but not for delivery into target cells. Residues 15 to 50 comprise the binding domain for SycE, a chaperone specific for YopE that is necessary for release and translocation of full-length YopE. To understand the role of this chaperone, we studied the delivery of YopE-Cya reporter proteins and YopE deletants by polymutant Yersinia devoid of most of the Yop effectors ([delta]HOPEM and [delta]THE strains). We first tested YopE-Cya hybrid proteins and YopE proteins deleted of the SycE-binding site. In contrast to wild-type strains, these mutants delivered YopE15-Cya as efficiently as YopE130-Cya. They were also able to deliver YopE [delta]17-77. SycE was dispensable for these deliveries. These results show that residues or codons 1 to 15 are sufficient for delivery into eukaryotic cells and that there is no specific translocation signal in Yops. However, the fact that the SycE-binding site and SycE were necessary for delivery of YopE by wild-type Yersinia suggests that they could introduce hierarchy among the effectors to be delivered. We then tested a YopE-Cya hybrid and YopE proteins deleted of amino acids 2 to 15 but containing the SycE-binding domain. These constructs were neither released in vitro upon Ca2+ chelation nor delivered into cells by wild-type or polymutant bacteria, casting doubts on the hypothesis that SycE could be a secretion pilot. Finally, it appeared that residues 50 to 77 are inhibitory to YopE release and that binding of SycE overcomes this inhibitory effect. Removal of this domain allowed in vitro release and delivery in cells in the absence as well as in the presence of SycE.H. and A. Brenninkmeijer ICP fellowship
EU TMR Programme Research Network contract FMRX-CT98-0164
Belgian Fonds National de la Recherche Scientifique Medicale
(Convention 3.4595.97)
Direction generale de la Recherche Scientifique-Communaute Francaise de Belgique
(Action de Recherche Concertee 94/99-172)
Interuniversity Poles of Attraction Program-Belgian State, Prime Minister\u27s Office,
Federal Office for Scientific, Technical and Cultural affairs (PAI 4/03)
SycE, a chaperone-like protein of Yersinia enterocolitica involved in Ohe secretion of YopE
No full textPathogenic yersiniae secrete a set of 11 anti-host proteins called Yops. The yop genes, scattered around the pYV plasmid, constitute a thermoinduced regulon controlled by the product of virF gene. The secretion of the Yops also requires the presence of the products of the other vir genes and operons, namely virA, virB and virC. The large virC operon and presumably some genes of the virA region encode a new secretion system. Mutations in any of these vir genes impair the production of all the Yops. In contrast, mutations in the yerA locus, located close to yopE, specifically abolish the expression of the cytotoxin YopE. We describe here the counterpart of yerA in Yersinia enterocolitica W22703. We demonstrate that the gene product of yerA regulates the production of YopE at a post-transcriptional level. It specifically binds the YopE protein. We consider that it acts as a specific chaperone and we call it SycE (for specific YopE chaperone). We hypothesize that SycE is a link between translation and the specific Yop export machinery. It is the first representative of a new family of pYV-encoded proteins
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
No full text“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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