Project description:Detection of immunogenic proteins remains an important task for life sciences as it nourishes the understanding of pathogenicity, illuminates new potential vaccine candidates and broadens the spectrum of biomarkers applicable in diagnostic tools. Traditionally, immunoscreenings of expression libraries via polyclonal sera on nitrocellulose membranes or screenings of whole proteome lysates in 2-D gel electrophoresis are performed. However, these methods feature some rather inconvenient disadvantages. Screening of expression libraries to expose novel antigens from bacteria often lead to an abundance of false positive signals owing to the high cross reactivity of polyclonal antibodies towards the proteins of the expression host. A method is presented that overcomes many disadvantages of the old procedures. We incorporated a fusion tag prior to our genes of interest and attached the expressed fusion proteins covalently on microarrays. This enhances the specific binding of the proteins compared to nitrocellulose. Thus, it helps to reduce the number of false positives significantly. It enables us to screen for immunogenic proteins in a shorter time, with more samples and statistical reliability. We validated our method by employing several known genes from Campylobacter jejuni NCTC 11168. Four of proteins that have previously been described as immunogenic have successfully been assessed immunogenic abilities with our method. One protein with no known immunogenic behaviour before suggested potential immunogenicity. The method presented offers a new approach for screening of bacterial expression libraries to illuminate novel proteins with immunogenic features. It could provide a powerful and attractive alternative to existing methods and help to detect and identify bacterial virulence factors, vaccine candidates and potential biomarkers. The overall study was done with five technical replicates. Ten proteins derived from Campylobacter jejuni were tested regarding their immunogenic potential. The ten proteins derived from Campylobacter jejuni were fusion proteins, i.e., N-terminal HaloTag fused to: Gene <--> Protein cjaA <--> putative amino-acid transporter periplasmic solute-binding protein hisJ <--> histidine-binding protein precursor pal <--> peptidoglycan associated lipoprotein flaC <--> flagellin flaA <--> flagellin peb1a <--> bifunctional adhesin/ABC transporter aspartate/glutamate-binding protein pyrC <--> dihydroorotase (EC:3.5.2.3) pseB <--> UDP-GlcNAc-specific C4,6 dehydratase/C5 epimerase gapA <--> glyceraldehyde 3-phosphate dehydrogenase (EC:1.2.1.12) argC <--> N-acetyl-gamma-glutamyl-phosphate reductase (EC:1.2.1.38)

Project description:Kallenberger2014 - CD95L induced apoptosis initiated by caspase-8, CD95 HeLa cells (cis/trans-cis/trans variant) The paper describes a new approach that combines single cell and population data in the same model. The model consists of a large number of single cell models, which are fitted to single cell data. Simultaneously, ensemble averages are fitted to population data. It is assumed that the kinetics in each cell can be described with the same kinetic parameters. Therefore, cell-to-cell variability is explained by variable initial protein concentrations. There are four variants of the model (with [CD95L]=500ng/ml = 16.6nM), i) cistrans (in CD95-HeLa cells) [ MODEL1403050000 ], ii) cistrans (in wild-type HeLa cells) [ MODEL1403050001 ], iii) cistrans-cistrans (in CD95-HeLa cells) [ MODEL1403050002 ], and iv) cistrans-cistrans (in wild-type HeLa cells) [ MODEL1403050003 ]. These model contain the equations for one "average cell" with median initial concentrations for CD95, FADD, p55, BID, PrNES_mCherry and PrER_mGFP. By integrating the model, it should be possible to obtain trajectories for PrER_mGFP, PrNES_mCherry, p43 and p18 similar as in Figure 4A (CD95-HeLa cells) and Figure 4B (wild-type HeLa cells). This model is described in the article: Intra- and Interdimeric Caspase-8 Self-Cleavage Controls Strength and Timing of CD95-Induced Apoptosis Stefan M. Kallenberger, Joël Beaudouin, Juliane Claus, Carmen Fischer, Peter K. Sorger, Stefan Legewie, and Roland Eils 11 March 2014: Vol. 7, Issue 316, p. ra23 Abstract: Apoptosis in response to the ligand CD95L (also known as Fas ligand) is initiated by caspase-8, which is activated by dimerization and self-cleavage at death-inducing signaling complexes (DISCs). Previous work indicated that the degree of substrate cleavage by caspase-8 determines whether a cell dies or survives in response to a death stimulus. To determine how a death ligand stimulus is effectively translated into caspase-8 activity, we assessed this activity over time in single cells with compartmentalized probes that are cleaved by caspase-8 and used multiscale modeling to simultaneously describe single-cell and population data with an ensemble of single-cell models. We derived and experimentally validated a minimal model in which cleavage of caspase-8 in the enzymatic domain occurs in an interdimeric manner through interaction between DISCs, whereas prodomain cleavage sites are cleaved in an intradimeric manner within DISCs. Modeling indicated that sustained membrane-bound caspase-8 activity is followed by transient cytosolic activity, which can be interpreted as a molecular timer mechanism reflected by a limited lifetime of active caspase-8. The activation of caspase-8 by combined intra- and interdimeric cleavage ensures weak signaling at low concentrations of CD95L and strongly accelerated activation at higher ligand concentrations, thereby contributing to precise control of apoptosis. This model is hosted on BioModels Database and identified by: BIOMD0000000525 . To cite BioModels Database, please use: BioModels Database: An enhanced, curated and annotated resource for published quantitative kinetic models . To the extent possible under law, all copyright and related or neighbouring rights to this encoded model have been dedicated to the public domain worldwide. Please refer to CC0 Public Domain Dedication for more information.

Project description:Kallenberger2014 - CD95L induced apoptosis initiated by caspase-8, wild-type HeLa cells (cis/trans variant) The paper describes a new approach that combines single cell and population data in the same model. The model consists of a large number of single cell models, which are fitted to single cell data. Simultaneously, ensemble averages are fitted to population data. It is assumed that the kinetics in each cell can be described with the same kinetic parameters. Therefore, cell-to-cell variability is explained by variable initial protein concentrations. There are four variants of the model (with [CD95L]=500ng/ml = 16.6nM), i) cistrans (in CD95-HeLa cells) [ MODEL1403050000 ], ii) cistrans (in wild-type HeLa cells) [ MODEL1403050001 ], iii) cistrans-cistrans (in CD95-HeLa cells) [ MODEL1403050002 ], and iv) cistrans-cistrans (in wild-type HeLa cells) [ MODEL1403050003 ]. These model contain the equations for one "average cell" with median initial concentrations for CD95, FADD, p55, BID, PrNES_mCherry and PrER_mGFP. By integrating the model, it should be possible to obtain trajectories for PrER_mGFP, PrNES_mCherry, p43 and p18 similar as in Figure 4A (CD95-HeLa cells) and Figure 4B (wild-type HeLa cells). This model is described in the article: Intra- and Interdimeric Caspase-8 Self-Cleavage Controls Strength and Timing of CD95-Induced Apoptosis Stefan M. Kallenberger, Joël Beaudouin, Juliane Claus, Carmen Fischer, Peter K. Sorger, Stefan Legewie, and Roland Eils 11 March 2014: Vol. 7, Issue 316, p. ra23 Abstract: Apoptosis in response to the ligand CD95L (also known as Fas ligand) is initiated by caspase-8, which is activated by dimerization and self-cleavage at death-inducing signaling complexes (DISCs). Previous work indicated that the degree of substrate cleavage by caspase-8 determines whether a cell dies or survives in response to a death stimulus. To determine how a death ligand stimulus is effectively translated into caspase-8 activity, we assessed this activity over time in single cells with compartmentalized probes that are cleaved by caspase-8 and used multiscale modeling to simultaneously describe single-cell and population data with an ensemble of single-cell models. We derived and experimentally validated a minimal model in which cleavage of caspase-8 in the enzymatic domain occurs in an interdimeric manner through interaction between DISCs, whereas prodomain cleavage sites are cleaved in an intradimeric manner within DISCs. Modeling indicated that sustained membrane-bound caspase-8 activity is followed by transient cytosolic activity, which can be interpreted as a molecular timer mechanism reflected by a limited lifetime of active caspase-8. The activation of caspase-8 by combined intra- and interdimeric cleavage ensures weak signaling at low concentrations of CD95L and strongly accelerated activation at higher ligand concentrations, thereby contributing to precise control of apoptosis. This model is hosted on BioModels Database and identified by: BIOMD0000000524 . To cite BioModels Database, please use: BioModels Database: An enhanced, curated and annotated resource for published quantitative kinetic models . To the extent possible under law, all copyright and related or neighbouring rights to this encoded model have been dedicated to the public domain worldwide. Please refer to CC0 Public Domain Dedication for more information.

Project description:Kallenberger2014 - CD95L induced apoptosis initiated by caspase-8, wild-type HeLa cells (cis/trans-cis/trans variant) The paper describes a new approach that combines single cell and population data in the same model. The model consists of a large number of single cell models, which are fitted to single cell data. Simultaneously, ensemble averages are fitted to population data. It is assumed that the kinetics in each cell can be described with the same kinetic parameters. Therefore, cell-to-cell variability is explained by variable initial protein concentrations. There are four variants of the model (with [CD95L]=500ng/ml = 16.6nM), i) cistrans (in CD95-HeLa cells) [ MODEL1403050000 ], ii) cistrans (in wild-type HeLa cells) [ MODEL1403050001 ], iii) cistrans-cistrans (in CD95-HeLa cells) [ MODEL1403050002 ], and iv) cistrans-cistrans (in wild-type HeLa cells) [ MODEL1403050003 ]. These model contain the equations for one "average cell" with median initial concentrations for CD95, FADD, p55, BID, PrNES_mCherry and PrER_mGFP. By integrating the model, it should be possible to obtain trajectories for PrER_mGFP, PrNES_mCherry, p43 and p18 similar as in Figure 4A (CD95-HeLa cells) and Figure 4B (wild-type HeLa cells). This model is described in the article: Intra- and Interdimeric Caspase-8 Self-Cleavage Controls Strength and Timing of CD95-Induced Apoptosis Stefan M. Kallenberger, Joël Beaudouin, Juliane Claus, Carmen Fischer, Peter K. Sorger, Stefan Legewie, and Roland Eils 11 March 2014: Vol. 7, Issue 316, p. ra23 Abstract: Apoptosis in response to the ligand CD95L (also known as Fas ligand) is initiated by caspase-8, which is activated by dimerization and self-cleavage at death-inducing signaling complexes (DISCs). Previous work indicated that the degree of substrate cleavage by caspase-8 determines whether a cell dies or survives in response to a death stimulus. To determine how a death ligand stimulus is effectively translated into caspase-8 activity, we assessed this activity over time in single cells with compartmentalized probes that are cleaved by caspase-8 and used multiscale modeling to simultaneously describe single-cell and population data with an ensemble of single-cell models. We derived and experimentally validated a minimal model in which cleavage of caspase-8 in the enzymatic domain occurs in an interdimeric manner through interaction between DISCs, whereas prodomain cleavage sites are cleaved in an intradimeric manner within DISCs. Modeling indicated that sustained membrane-bound caspase-8 activity is followed by transient cytosolic activity, which can be interpreted as a molecular timer mechanism reflected by a limited lifetime of active caspase-8. The activation of caspase-8 by combined intra- and interdimeric cleavage ensures weak signaling at low concentrations of CD95L and strongly accelerated activation at higher ligand concentrations, thereby contributing to precise control of apoptosis. This model is hosted on BioModels Database and identified by: BIOMD0000000526 . To cite BioModels Database, please use: BioModels Database: An enhanced, curated and annotated resource for published quantitative kinetic models . To the extent possible under law, all copyright and related or neighbouring rights to this encoded model have been dedicated to the public domain worldwide. Please refer to CC0 Public Domain Dedication for more information.

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Exocyst protein subnetworks integrate Hippo and mTOR signaling to promote virus detection and cancer

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