It has been theorized that most proteins are under selection pressure to be soluble in crowded cellular spaces. To maintain solubility a proteins’ aggregation propensity should be inversely proportional to their maximum likely concentration. This theory was examined by comparing the proteome of the model organism S. cerevisiae, which has previously undergone a Whole Genome Duplication (WGD) event to the proteome of the closely related yeast K. waltii, which has not undergone WGD. This comparison revealed the following: 1) Predicted aggregation propensities are higher in S. cerevisiae than K. waltii. 2) Aggregation propensity does not predict which genes reverted to a single copy after WGD. 3) In genes which were retained as duplicates in S. cerevisiae after WGD, aggregation propensities rose from the inferred common ancestral protein. 4) Genes retained as duplicates showed less of an increase relative to their homologues in K. waltii than genes which were not retained as duplicates. 5) The relationship between the log predicted aggregation propensity and log mRNA expression level or log protein abundance was not linear as previously predicted. These results suggest that while there is broad selection pressure for reduced aggregation pressure for genes which have been duplicated, the precise relationship between aggregation propensity and gene expression is more complicated than previously predicted. These results also allow speculation that the whole genome duplication in S.cerevisiae may have been made possible by a general relaxation of aggregation-related selection pressure. / text

In Saccharomyces cerevisiae, DNA replication initiates at distinct origins termed Autonomously Replicating Sequences (ARSs). A key element in ARS is the ACS/B1 sequence, which binds the Origin Recognition Complex (ORC). During early G1 phase, the pre-replication complex is assembled by ORC. These ARSs are termed replicators. In yeast, ORC is also involved in gene silencing. These loci also contain an ACS/B1 element; however at these positions ORC recruits the silencing SIR complex. ARSs found here are termed silencers. Therefore, ARSs have a dual function. Research has also shown that origin ARSs can be substituted for silencing ARSs and vice versa. Since a mutation in ACS abolishes replication activity, studies have turned to the B1 element to account for the functional duality, but results have been mixed. I hypothesize that the B1 element plays a key role in the dual nature of ARS. To test this hypothesis, silencer and replicator ARSs were subjected to site directed mutagenesis around the WTW motif of the B1 element. Their efficiency was then tested using routine silencing and replication assays. Results reveal that the silencing ability of silencer ARSs is unaffected by these mutations; however mutations within and around the WTW motif reduce silencing efficiency of replicator ARSs. Sequence alignments have also shown that silencer ARSs have a broader WTW consensus than replicator ARSs. Preliminary replication assays are consistent with the above results and other research, contributing to a conclusion that the B1 element is not the sole determining factor in the dual nature of ARS. / NSERC

No description available.

Unstable oil markets with rising environmental concerns have revived widespread interest in production of fuel ethanol from renewable materials. Cellulosic materials are abundant and prominent feedstocks for cheap ethanol production. However, due to recalcitrant structure of these materials, pretreatment is a prerequisite. Depending on the biomass, pretreatment and hydrolysis conditions, a number of degradation products and/or toxic components may be released that show strong inhibitory effects on the fermenting microorganisms. This thesis deals with application of encapsulation technology to ferment the highly toxic hydrolyzates without further pretreatment. Free cells could not tolerate presence of 5 g/l furfural in defined medium, and inhibitors in wood and peel hydrolyzates in batch mode of operation and fermentation failed. Continuous cultivation of wood hydrolyzate was only successful at 0.1 h−1 and the majority of cells lost their viability after 5 retention times. Encapsulated cell system could successfully ferment the synthetic medium containing 5 g/l furfural during sequential batch cultivations with ethanol yield of 0.41-0.42 g/g. Cultivation of undetoxified hydrolyzates was also carried out, where glucose and mannose were converted within 10 h without significant lag phase. However, a gradual decrease in cell activity was observed in sequential batches. Continuous cultivation was more successful, and wood hydrolyzate was fermented to ethanol by encapsulated S. cerevisiae at dilution rates up to 0.5 h−1. More than 75% of the encapsulated cells were viable in the worst conditions. Ethanol was produced with yield 0.44 g/g and specific productivity 0.14–0.17 g/g•h at all dilution rates. Contrary to wood hydrolyzate, where there is no preference for permeation of sugars or inhibitors through the capsules’ membrane, encapsulation technology was applied to eliminate inhibition of limonene in fermentation of orange wastes to ethanol. The capsules’ membrane, of hydrophilic nature, is practically impermeable to hydrophobic compounds such as limonene while allowing penetration of nutrients and products. While presence of 0.1% v/v limonene in the medium results in strong inhibition or even failure of cultivation with free cells, using this technique allowed fermentation of a medium containing 1.5% v/v limonene. The impact of encapsulation on the anaerobic growth pattern, morphological and physiological changes of S. cerevisiae over long-term application was investigated. The growth rate, total RNA and protein content of the encapsulated cells decreased gradually over repeated batch cultivations, while stored carbohydrates content increased. Within 20 batch cultivations, total RNA and protein content of encapsulated cells decreased by 39% and 24%, whereas glycogen and trehalose content increased by factors of 4.5 and 4, respectively. / <p>Akademisk avhandling som för avläggande av teknologie doktorsexamen vid Chalmers tekniska högskola försvaras vid offentlig disputation den 18 april 2008.</p>

Production of ammonia by the colonies of mutants and aging of wrinkled colonies of Saccharomyces cerevisiae The aim of this diploma thesis is to observe the development, respectively the aging of cells in yeast colonies Saccharomyces cerevisiae. Yeast cells S. cerevisiea form multicellular organized structures on a solid substrate, i.e. colonies, which the intercellular interactions occur in. These interactions influence forming, morphology and aging of yeast colonies. This diploma thesis is focused partly on the changes in ammonia production by giant colonies of deletion mutants and partly on the aging of colonies with the wrinkled morphology. I characterized mutant strains of S. cerevisiae with the deletion in RTG1, RTG2, RTG3, FIS1, CIT2 genes. Their products play an important role in the colony development. The transcription of these genes changes during the transition from the acidic to alkali phase during developmental process of the colonies. I have found out that the ammonium production rate was in accordance with the results of the alkalization in giant colonies surroundings and mentioned mutants derived from the BY strain has been producing ammonia since the 15th day. The rate of the ammonia production by rtg3∆ strain was comparable to the parental strain. Compared to parental strain, lower...

El llevat S.cerevisiae és un dels models eucariotes més adequats per l'estudi dels diversos mecanismes implicats en la supervivència cel.lular en resposta a estrès oxidatiu. Les espècies reactives d'oxigen (ROS) com els radicals hidroxil, l'anió superòxid o el peròxid d'hidrogen generen estrès oxidatiu, causant important danys intracel.lulars davant els quals la cèl.lula a desenvolupat una sèrie de mecanisme per fer-hi front. Grx3 i Grx4 són dues glutaredoxines monotiòliques de S.cerevisisae que formen part dels sistemes enzimàtics que regulen l'estat redox de les proteïnes en resposta a estrès oxidatiu. No obstant, fins ara es desconeixen els mecanismes amb els quals Grx3 i Grx4 participen en la detoxificació d'aquestes ROS i en l'adaptació cel.lular en condicions oxidatives. En el primer Capítol es caracteritza el paper funcional de Grx3 i Grx4 en la regulació de l'homeòstasi del ferro intracel.lular mitjançant la regulació del factor transcripcional Aft1, encarregat de regular la transcripció de gens que formen part del sistema d'alta afinitat de captació de ferro. A més a més, es caracteritza el paper funcional dels dominis glutaredoxina (GRX) de Grx3 i Grx4 en l'exportació nuclear d'Aft1, com a mecanisme regulador de l'estrès oxidatiu generat per un augment en els nivells de ferro intracel.lulars. En el segon Capítol hem aconseguit donar una funció específica per Grx3 i Grx4 en la regulació de la via d'integritat cel.lular o la via PKC1- MAP quinasa en resposta a estrès oxidatiu. A més a més, demostrem que són els dominis tioredoxina (TRX) de Grx3 i Grx4 qui dessarrollen el paper protagonista en l'activació de la quinasa Slt2 en resposta a estrès oxidatiu i en la repolarització del citoesquelet d'actina en condicions normals i en resposta a estrès oxidatiu. També demostrem que Grx3, Grx4 i Slt2 estàn relacionades genètica i funcionalment amb els procesos implicats en l'organització del citoesquelet d'actina en resposta a estrès oxidatiu i en la biogènesi vacuolar en condicions normals. / La levadura S.cerevisiae es uno de los modelos eucariotas más adecuados para el estudio de los diferentes mecanismos implicados en la supervivencia celular en respuesta a estrés oxidativo. Las especies reactivas de oxígeno (ROS) como los radicales hidroxilo, el anión superóxido o el peróxido de hidrógeno generan estrés oxidativo, induciendo importantes daños intracelulares frente a los cuales la célula tiene que desarrollar una serie de mecanismos para hacerles frente. Grx3 i Grx4 son dos glutaredoxinas monotiólicas de S.cerevisiae que forman parte de los sistemas enzimáticos que regulan el estado redox de las proteínas en respuesta a estrés oxidativo. No obstante, hasta hoy se desconocen los mecanismos mediante los cuales Grx3 i Grx4 participan en la detoxificación de estos ROS y en la adaptación celular frente a condiciones oxidativas. En el primer Capítulo se caracteriza el papel funcional para Grx3 y Grx4 en la regulación de la homeóstasis del hierro intracelular mediante el factor transcripcional Aft1, el cual se encarga de regular la transcripción de genes que forman parte del sistema de alta afinidad de captación de hierro. Además, se caracteriza el papel funcional de los dominios GRX de Grx3 y Grx4 en la exportación nuclear de Aft1, como mecanismo regulador del estrés oxidativo generado por un aumento en los niveles de hierro intracelulares. En el segundo Capítulo hemos logrado dar una función específica a Grx3 y Grx4 en la regulación de la vía de integridad celular o vía PKC1-MAP quinasa en respuesta a estrés oxidativo. Además, tras diseccionar los dominios glutaredoxina (GRX) y tioredoxina (TRX) de Grx3 y Grx4, hemos concluido que son los dominios TRX de ambas glutaredoxinas quienes poseen un papel protagonista en la activación de la quinasa Slt2 en respuesta a estrés oxidativo y en la reorganización del citoesqueleto de actina en condiciones normales y oxidantes. También se demuestra que Grx3, Grx4 y Slt2 están relacionados genética y funcionalmente en los procesos implicados en la organización del citoesqueleto d'actina en respuesta a estrés oxidativo y en la biogénesis vacuolar en condiciones normales. / The yeast S.cerevisiae is one of the most suitable eukaryotic models to study several mechanisms involved in cell survival in the response to oxidative stress. Reactive oxygen species (ROS) such as hydroxyl radicals, superoxide anions or hydrogen peroxide provoque oxidative stress and cause important cell damage. As a consequence of that, cells need to develop a series of mechanisms in order to repair their structures. Grx3 and Grx4 are two monothiol glutaredoxins of S.cerevisiae potentially involved in enzymatic systems to regulate the redox state of proteins in front of oxidative stress. Nevertheless, actually is unknown the mechanisms where Grx3 and Grx4 participate in ROS detoxification and in the cellular adaptation to oxidative conditions. In the first chapter, we characterize a functional role for both Grx3 and Grx4 in the maintenance of iron homeostasis through the regulation of Aft1, a transcription factor involved in the transcriptional regulation of a subset of genes which integrate the high affinity iron uptake system. In addition, we have characterized the functional role for both GRX domains of Grx3 and Grx4 in the nuclear export of Aft1 as a mechanism that regulates the oxidative stress generated by high levels of intracellular iron. In the second chapter, it is characterized a specific function for Grx3 and Grx4 in the regulation of the cell integrity pathway or PKC1-MAP kinase pathway in response to oxidative stress. Moreover, we described the functional role for both TRX domains of Grx3 and Grx4 in the Slt2 activation in response to oxidative stress and in the reorganization of the actin cytoskeleton in normal and oxidant conditions. We also demonstrated the genetic and the functional relationship between Grx3, Grx4 and Slt2 in the mechanisms involved in the actin cytoskeleton organization in response to oxidative stress and in the vacuolar biogenesis in normal conditions.

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No. of bitstreams: 2 Dissertação - Késia de Souza Cruz - 2016.pdf: 2312278 bytes, checksum: 9388f7c21e3443036e7ad2c1d3256ed1 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-05-02 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Recent studies show that often, pathologies are caused by Reactive oxygen species (ROS). The ROS are associated with the oxidative stress in the cells. The body uses the antioxidants to defend itself from the consequences of this process. An example of an antioxidant with different functions in an organism is the Glutathione (GSH). It is a cellular thiol with low molecular mass, that’s synthesized by chemical, enzymatic and fermentative methods. Since it is environmentally and economically viable, the use of the fermentative process has gained scientific visibility. The use of mathematical models is an alternative that helps in the production of Glutathione. Considering these observations, the present study's aimed to elaborate a mathematical model for production and prediction of GSH for Saccharomyces cerevisiae, as well as to validate its numerical optimization experimentally. For the mathematical model in this process, was used the Central Composite Rotational Design 2², having as an answer, the GSH and biomass values in function with the concentration of molasses and glycerol during a period of 96 hours of fermentation. Based on these results, a hybrid model was made, having as a result, the specific rate of GSH formation. The final model was adjusted to a polynomial function using the method of least squares. Experimentally, the maximum production of GSH was found to be, in 72 hours (119,6 mg L-1) using 76,9 g L-1of molasses and glycerol, respectively. Applying the model for similar conditions, it was estimated to a 118,6mg L-1. The experimental results were then statistically analyzed to verify their similarity. The numerical optimization was made by setting the clock for 72 hours. At this step, the concentration of molasses and glycerol were varied until the best conditions to produce GSH were met. The optimization helped to derive an estimate that 70 g L-1of sugar cane molasses and 40 g L-1of glycerol can guarantee the production of 126 mg L-1of GSH. Based on the accuracy of the observations, the same conditions were used as a central point for the validation of the model - Factorial Design2². The results obtained under these conditions helped establish that the central point of the proposed design for the validation of the model, is 127,3mg L-1of GSH in 72 hours. The validation of this mathematical model by the numerical optimization proved that it was effective for the production and prediction of Glutathione by Saccharomyces cerevisiae, using industrial by-products. / Estudos recentes mostram que as patologias mediadas por espécies reativas de oxigênio (ERO) estão frequentes. As EROs associam-se ao estresse oxidativo nas células, e para o corpo defender-se das consequências advindas desse processo, utiliza os antioxidantes. Um exemplo de antioxidante com variadas funções no organismo é a glutationa (GSH). Trata-se de um tiol celular de baixa massa molecular, que pode ser sintetizada por via química, enzimática e fermentativa. Devido sua viabilidade ambiental e econômica, o uso de processos fermentativos tem ganhado visibilidade científica. O emprego de modelos matemáticos é uma alternativa que auxilia na predição deste antioxidante. Tendo em vista estas observações o presente trabalho teve como objetivo elaborar um modelo matemático de predição da produção de GSH por S. cerevisiae, bem como validar experimentalmente sua otimização numérica. Para a confecção do modelo matemático utilizou-se um Delineamento Composto Central Rotacional 2², tendo como resposta os valores de GSH e biomassa em função das concentrações de melaço e glicerol durante 96 horas de fermentação. A partir desses resultados foi confeccionado um modelo híbrido, tendo como resposta a velocidade específica de formação de GSH. O modelo final foi ajustado a uma função polinomial utilizando metodologia dos Mínimos Quadrados. Experimentalmente a máxima produção de GSH foi encontrada em 72 horas (119,6 mg L-1) utilizando 76,9 g L-1 de melaço e glicerol, respectivamente. Aplicando o modelo para as mesmas condições estimou-se 118,6 mg L-1. Os resultados experimentais e preditos foram analisados estatisticamente para verificar a similaridade dos mesmos. A otimização numérica foi feita fixando o tempo em 72 horas. Nessa etapa variaram-se as concentrações de melaço e glicerol até obter a melhor condição para produzir GSH. A otimização estimou que 70 g L-1de melaço de cana-de-açúcar e 40 g L-1 de glicerol podem garantir uma produção de 126 mg L-1 de GSH. Tendo em conta esta constatação, essas condições foram utilizadas como ponto central de um Delineamento Fatorial Completo 2² para validação do modelo. O resultado encontrado nas mesmas condições do ponto central do delineamento proposto para validação foi de 127,3 mg L-1 de GSH em 72 horas. A validação do modelo matemático por meio de otimização numérica comprovou que o uso da modelagem foi eficaz para a predição da produção de glutationa por Saccharomyces cerevisiae utilizando subprodutos industriais.

Récemment, des analyses dans divers organismes eucaryotes ont révélé que l'ensemble du génome est transcrit et produit en plus des ARNs messagers, une grande variété d’ARNs non codants de différentes longueurs. Les ARNs non codants de plus de 200 nucleotides, classés comme longs ARNs non codants (LARNnc), représentent la classe la plus abondante de transcripts non codants. Les études des fonctions des LARNnc suggèrent que beaucoup d'entre eux seraient impliqués dans la régulation de la transcription. L'objectif de ma thèse de doctorat était d'élucider les mécanismes de la régulation transcriptionnelle médiée par des LARNnc dans différents systèmes eucaryotes. Dans mon premier projet, j'ai étudié le rôle d'un long ARN non codant antisens dans la régulation transcriptionnelle du gène PHO84, codant un transporteur de phosphate à haute affinité, chez S. cerevisiae. Des études antérieures ont montré que la suppression d’une proteine de l’exosome Rrp6 entraîne une augmentation de l'expression antisens et la répression de PHO84. Il a été suggéré que la perte de Rrp6 entraîne une stabilisation antisens au locus PHO84, entraînant le recrutement de l'histone de-acétylase Hda1 et la répression de PHO84. Cependant, le mécanisme par lequel Rrp6p régule la transcription de PHO84 n’était pas connu. En combinant des méthodes à l’échelle de cellule unique, des approches biochimiques et génétiques, nous avons montré que les niveaux d'ARN antisens sont régulés principalement lors de l'élongation par le complexe Nrd1-Nab3-Sen1, qui nécessite Rrp6 pour un recrutement efficace à l`extrémité 3`de PHO84. De plus, nous révélons l'expression anticorrelé du sens et de l'antisens, En résumé, nos données suggèrent que la transcription antisens régule le seuil d'activation du promoteur PHO84. Dans mon second projet, j'ai étudié les rôles des ARNs dérivés des amplificateurs (ARNa) dans la regulation de la transcription. En utilisant les cellules de cancer du sein MCF7 comme système modèle, nous avons cherché à déterminer comment les ARNa induits par l'oestrogène (E2) participent à la régulation de la transcription médiée par le recepteur d’oestrogène (ERα) au niveau de l'allèle unique. À l'aide de l’hybridation fluorescente à l’échelle de molécule unique (smFISH), nous avons révélé qu`après induction d'E2, les ARNa sont induits avec une cinétique similaire à celle des ARNm cibles, sont localisés exclusivement dans le noyau, principalement associés à la chromatine, et sont moins abondants que les ARNm. De manière surprenante, nous avons constaté que les ARNa sont rarement co-transcrits avec leurs loci cibles, indiquant que la transcription active des gènes ne nécessite pas la synthèse continue ou l'accumulation d'ARNa sur l'amplificateur. En outre, en utilisant des mesures de la distance à sous-diffraction, nous avons démontré que la cotranscription des ARNa et des ARNm se produit rarement dans une boucle amplificateurpromoteur. De plus, nous avons révélé que la transcription basale d'ARNa n'exige pas ERα ou l'histone méthyltransférase MLL1 qui active l'amplificateur par la mono-méthylation H3K4. Dans l'ensemble, nos résultats ont montré que les ARNa peuvent jouer un rôle lors de l'activation du promoteur, mais ne sont pas nécessaires pour maintenir la transcription de l'ARNm ou pour stabiliser les interactions amplificateur-promoteur. / Transcription is the initial step in gene expression and is subject to extensive regulation. Recently, analyses in diverse eukaryotes have revealed that in addition to protein coding genes, transcription occurs throughout the noncoding genome, producing non-coding RNAs of various lengths. Non-coding RNAs longer than 200 nucleotides, classified as long non-coding RNAs (lncRNAs), represent the most abundant class of non-coding transcripts, whose functions however are poorly understood. Recent studies suggest that many lncRNAs might have roles in transcription regulation. The goal of my PhD thesis was to elucidate the mechanisms of lncRNA mediated transcription regulation in different eukaryotic systems. For my first project, I investigated the role of an antisense long noncoding RNA in transcription regulation of the high-affinity phosphate transporter gene PHO84 in the unicellular eukaryote S. cerevisiae. Previous studies showed that deletion of the nuclear exosome component Rrp6 results in increased antisense expression and repression of PHO84. It was suggested that the loss of Rrp6 results in antisense stabilization at the PHO84 locus, leading to recruitment of the histone de-acetylase Hda1 and repression of PHO84. However, most of the mechanistic details of how Rrp6p functions in regulating PHO84 transcription were not understood. Combining single cell methods with biochemical and genetic approaches, we showed that antisense RNA levels are regulated primarily during transcriptional elongation by the Nrd1-Nab3-Sen1 complex, which requires Rrp6 for efficient recruitment to the 3’end of PHO84. Furthermore, we reveal anti-correlated expression of sense and antisense, which have distinct modes of transcription. In summary, our data suggest a model whereby antisense transcriptional read-through into the PHO84 promoter regulates the activation threshold of the gene. For my second project, I investigated the roles of enhancer derived RNAs (eRNAs). eRNAs are lncRNAs transcribed from enhancers that have been suggested to regulate transcription through different mechanisms, including enhancer-promoter looping, RNA polymerase elongation, and chromatin remodeling. However, no coherent model of eRNA function has yet emerged. Using MCF7 breast cancer cells as a model system, we sought to determine how estrogen (E2) induced eRNAs participate in estrogen receptor alpha (ERα) mediated transcription regulation at the single allele level. Using single molecule fluorescent in situ hybridization (smFISH), we revealed that upon E2 induction eRNAs are induced with similar kinetics as target mRNAs, but are localized exclusively in the nucleus, mostly chromatin associated, and are less abundant than mRNAs. Surprisingly, we found that eRNAs are rarely co-transcribed with their target loci, indicating that active gene transcription does not require the continuous synthesis or accumulation of eRNAs at the enhancer. Furthermore, using sub-diffraction-limit distance measurements, we demonstrated that co-transcription of eRNAs and mRNAs rarely occurs within a closed enhancer-promoter loop. Moreover, we revealed that basal eRNA transcription does not require ERα or the histone methyltransferase MLL1, which activates the enhancer through H3K4 mono-methylation. Altogether, our findings showed that eRNAs may play a role during promoter activation, but are not required to sustain mRNA transcription or stabilize enhancer-promoter looping interactions.

Information spielt in der Natur eine zentrale Rolle. Als intrinsischer Teil des genetischen Codes ist sie das Grundgerüst jeder Struktur und ihrer Entwicklung. Im Speziellen dient sie auch Organismen, ihre Umgebung wahrzunehmen und sich daran anzupassen. Die Grundvoraussetzung dafür ist, dass sie Information ihrer Umgebung sowohl messen als auch interpretieren können, wozu Zellen komplexe Signaltransduktionswege entwickelt haben. In dieser Arbeit konzentrieren wir uns auf Signalprozesse in S.cerevisiae die von osmotischem Stress (High Osmolarity Glycerol (HOG) Signalweg) und der Stimulation mit α-Faktor (Pheromon Signalweg) angesprochen werden. Wir wenden stochastische Modelle an, die das intrinsische Rauschen biologischer Prozesse darstellen können, um verstehen zu können wie Signalwege die ihnen zur Verfügung stehende Information umsetzen. Informationsübertragung wird dabei mit einem Ansatz aus Shannons Informationstheorie gemessen, indem wir sie als einen Kanal in diesem Sinne auffassen. Wir verwenden das Maß der Kanalkapazität, um die Genauigkeit des Phosphorelays einschränken zu können. In diesem Modell, simuliert mit dem Gillespie Algorithmus, können wir durch die Analyse des Signalverhaltens den Parameterraum zusätzlich stark einschränken. Eine weitere Herangehensweise der Signalverarbeitung beschäftigt sich mit dem “Crosstalk” zwischen HOG und Pheromon Signalweg. Wir zeigen, dass die Kontrolle der Signalspezifizität vor allem bei Scaffold-Proteinen liegt, die Komponenten der Signalkaskade binden. Diese konservierten Motive zellulärer Signaltransduktion besitzen eine geeignete Struktur, um Information getreu übertragen zu können. Im letzten Teil der Arbeit untersuchen wir potentielle Gründe für die evolutionäre Selektion von Scaffolds. Wir zeigen, dass ihnen bereits durch die Struktur des Mechanismus möglich ist, Informationsgenauigkeit zu verbessern und einer verteilten Informationsweiterleitung sowohl dadurch als auch durch ihre Robustheit überlegen sind. / Information plays a ubiquitous role in nature. It provides the basis for structure and development, as it is inherent part of the genetic code. It also enables organisms to make sense of their environments and react accordingly. For this, a cellular interpretation of information is needed. Cells have developed sophisticated signaling mechanisms to fulfill this task and integrate many different external cues with their help. Here we focus on signaling that senses osmotic stress (High Osmolarity Glycerol (HOG) pathway) as well as α-factor stimulation (pheromone pathway) in S.cerevisiae. We employ stochastic modeling to simulates the inherent noisy nature of biological processes to assess how systems process the information they receive. This information transmission is evaluated with an information theoretic approach by interpreting signal transduction as a transmission channel in the sense of Shannon. We use channel capacity to both constrain as well as quantify the fidelity in the phosphorelay system of the HOG pathway. In this model, simulated with the Gillespie Algorithm, the analysis of signaling behavior allows us to constrain the possible parameter sets for the system severely. A further approach to signal processing is concerned with the mechanisms that conduct crosstalk between the HOG and the pheromone pathway. We find that the control for signal specificity lies especially with the scaffold proteins that tether signaling components and facilitate signaling by trans-location to the membrane and shielding against miss-activation. As conserved motifs of cellular signal transmission, these scaffold proteins show a particularly well suited structure for accurate information transmission. In the last part of this thesis, we examine the potential reasons for an evolutionary selection of the scaffolding structure. We show that due to its structure, scaffolds are increasing information transmission fidelity and outperform a distributed signal in this regard.