Phosphofructokinase from Escherichia coli (EcPFK) is allosterically regulated by MgADP and phospho(enol)pyruvate (PEP). Both molecules compete for binding to the same allosteric site, however, MgADP activates and PEP inhibits the binding of fructose-6-phosphate (F6P) to the active site. The mode by which this enzyme can differentiate between the two ligands and cause the appropriate response is important for the understanding of the basis of allosteric regulation. We studied the interactions between an active site and an allosteric site (heterotropic interactions) within the protein, and found that each of the four unique heterotropic interactions is unique and the magnitudes of the coupling free energies for MgADP activation sum up to 100% that of wildtype EcPFK without homotropic cooperativity in F6P binding. We took on the kinetic and structural characterization of phosphofructokinase from Lactobacillus bulgaricus (LbPFK) to reveal an enzyme that exhibits allosteric properties in spite of previous kinetic studies performed by Le Bras et al. (1991). We have identified residues in EcPFK (Asp59, Gly184 and Asp273), which are important for the allosteric responses to both MgADP and PEP. Interestingly, Lys214 is only important in PEP inhibition and not MgADP activation. We can also differentially disrupt the MgADP heterotropic interactions with the introduction of G184C within the protein. These results suggest that there are different pathways for allosteric communication within the enzyme: different paths for MgADP activation and PEP inhibition, and different paths for each heterotropic interaction with Gly184 being important for the 33Å MgADP heterotropic interaction.

Techn. Univ., Diss., 2005--Darmstadt

Submitted by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2015-01-08T15:36:43Z No. of bitstreams: 2 cleya_silva_santana_cruz.pdf: 3196384 bytes, checksum: ab5bc76d3c89cdad0a8a51f5bad61c79 (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2015-01-08T15:37:58Z (GMT) No. of bitstreams: 2 cleya_silva_santana_cruz.pdf: 3196384 bytes, checksum: ab5bc76d3c89cdad0a8a51f5bad61c79 (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) / Approved for entry into archive by Rodrigo Martins Cruz (rodrigo.cruz@ufvjm.edu.br) on 2015-01-08T15:38:17Z (GMT) No. of bitstreams: 2 cleya_silva_santana_cruz.pdf: 3196384 bytes, checksum: ab5bc76d3c89cdad0a8a51f5bad61c79 (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) / Made available in DSpace on 2015-01-08T15:38:17Z (GMT). No. of bitstreams: 2 cleya_silva_santana_cruz.pdf: 3196384 bytes, checksum: ab5bc76d3c89cdad0a8a51f5bad61c79 (MD5) license_rdf: 23898 bytes, checksum: e363e809996cf46ada20da1accfcd9c7 (MD5) Previous issue date: 2013 / Funda??o de Amparo ? Pesquisa do estado de Minas Gerais (FAPEMIG) / Funda??o Diamantinense de Apoio ao Ensino, Pesquisa e Extens?o (Fundaep) / O Programa de Educa??o Permanente para M?dicos da Estrat?gia de Sa?de da Fam?lia foi implantado na Regi?o Ampliada de Sa?de Jequitinhonha em outubro de 2010, com a finalidade de melhorar o n?vel de resolubilidade da Aten??o Prim?ria ? Sa?de, tomando como ponto de partida a aprendizagem significativa e integrada das diversas compet?ncias cl?nicas necess?rias aos m?dicos das equipes de sa?de da fam?lia. O objetivo deste trabalho foi avaliar as a??es de planejamento, execu??o e resultados do PEP na Regi?o Ampliada de Sa?de Jequitinhonha de Minas Gerais em interface com os objetivos propostos pelo Programa. O estudo foi desenvolvido em 14 munic?pios desta Regi?o, que possu?am m?dicos da Estrat?gia de Sa?de da Fam?lia com frequ?ncia de participa??o no PEP igual ou superior a 60,0%. Participaram da pesquisa 14 gestores municipais de sa?de, 31 m?dicos e 383 usu?rios. Tratou-se de uma pesquisa de triangula??o descritiva, quantitativa e qualitativa. Utilizou-se como instrumentos de coleta de dados: 1) Question?rios estruturados dirigidos aos usu?rios, m?dicos e gestores de sa?de; 2) Relat?rios de supervisores dos GAPs para o levantamento dos temas estudados nos encontros e 3) Atestos de gestores municipais de sa?de para calcular a rotatividade profissional dos m?dicos. As entrevistas das consultas m?dicas foram filmadas e analisadas. Utilizou-se a an?lise descritiva dos dados, o teste do qui-quadrado e teste de Fisher (p = 0,05). A m?dia de idade dos m?dicos entrevistados foi de 39,5 anos, 67,7% eram do sexo masculino e 48,2% solteiros. Em rela??o ? titula??o, 45,2% dos m?dicos possu?am apenas gradua??o em medicina, sendo que 35,5% possu?am no m?ximo quatro anos de forma??o. A rela??o m?dicos inscritos/presentes nos encontros do PEP foi de 41,5% em 2011 e 38,4% em 2012. Os temas mais estudados nos encontros de GAP foram a metodologia do PEP (24,3%) e as doen?as cr?nicas n?o transmiss?veis (10,5%). Para os m?dicos participantes, o supervisor do GAP segue a metodologia proposta e os materiais atendem ?s necessidades dos grupos (100,0%). Os m?dicos (93,5% e 96,8%, respectivamente) relatam que ap?s a participa??o no PEP houve redu??o de encaminhamentos e de pedidos de exames desnecess?rios. Os m?dicos participantes (93,5%) afirmam ainda que suas consultas foram reestruturadas ap?s a participa??o no Programa. Segundo o ponto de vista de 35,7% dos gestores municipais de sa?de, os m?dicos vinculados a seus munic?pios participam do PEP apenas como forma de cumprir o Contrato do Programa Sa?de em Casa, mas para a maioria (62,5%) este n?o ? o motivo da participa??o, enquanto 50% dos Secret?rios Municipais de Sa?de afirmam que os m?dicos que s?o liberados para o PEP, n?o comparecem nos encontros. A maioria dos usu?rios (76,1%) relatou ter percebido melhora no atendimento ap?s a participa??o do m?dico no Programa. O ?ndice de rotatividade para os m?dicos que participam do PEP com frequ?ncia igual ou superior a 60,0% foi de 35,5%, enquanto para aqueles que n?o participam efetivamente do Programa o valor foi de 60,9%. Conclui-se, assim, que a Educa??o Permanente nos moldes do PEP pode melhorar o desempenho cl?nico dos m?dicos e envolver mais o usu?rio em seu tratamento, al?m de contribuir para a fixa??o de profissional na regi?o. / Disserta??o (Mestrado Profissional) ? Programa de P?s-Gradua??o em Sa?de, Sociedade e Ambiente, Universidade Federal dos Vales do Jequitinhonha e Mucuri, 2013. / ABSTRACT The Permanent Education Program for Physicians in the Family Health Strategy was implemented in the Jequitinhonha Extended Health Region in October 2010 for the purpose of improving the level of resolution capability in Primary Health Care. It took as the starting point the significant and integrated learning of the various clinical skills that the physicians in the family health teams need. The objective of this paper was to assess the planning and execution actions, as well as the results of the PEP in the Jequitinhonha Extended Health Region, in Minas Gerais state, in interface with the objectives proposed by the Program. The study was developed in 14 municipalities in this Region, which had physicians from the Family Health Strategy whose participation rate in the PEP was equal to or greater than 60 percent. 14 health managers, 31 physicians, and 383 users participated in the research. The research used a descriptive, quantitative, and qualitative triangulation approach. The following data collection tools were used: 1) Structured questionnaires addressed to users, physicians, and health managers; 2) Reports by supervisors from the Professional Development Groups (PDGs) for an overview of the topics studied in the meetings, and 3) Statements by municipal health managers to calculate the professional turnover rate of medical doctors. The interviews during medical appointments were filmed and analyzed. Descriptive data analysis, the?chi-square test? and the Fisher Test (p = 0.05), and the Pearson Correlation Test (p = 0.0.5%) were used. The average age of the interviewed physicians was 39.5 years; 67.7% were males, and 48% were single. As far as academic degree was concerned, 45.2% of the physicians only had a degree in Medicine, and 35.5% of them had graduated no more than four years prior to these interviews. The percentages of physicians who signed up for / participated in the meetings of the PEP were 41.5% in 2011 and 38.4% in 2012. The most widely studied topics in the Professional Development Group meetings were the methodology of the Permanent Education Program (24.3%) and chronic non-communicable diseases (10.5%). For the participating physicians, the supervisor of the Professional Development Group follows the proposed methodology, and the materials meet the needs of the groups (100%). The physicians (93.5% and 96.8%, respectively) reported that, after participating in the Permanent Education Program, there was a reduction in the number of unnecessary referrals and requests for medical examinations. The participating physicians (93.5%) also stated that their medical consultations were restructured after they participated in the Program. From the point of view of 35.7% of the municipal health managers, the physicians working in their municipalities attend the Permanent Education Program only to comply with the Home Health Care Program Agreement. However, for most of the municipal health care managers (62.5%), this is not the reason why physicians attend the PEP, while 50% of the Municipal Health Secretaries stated that physicians who are released to attend the PEP do not show up for the meetings. Most of the users (76.1%) reported that they noticed an improvement in the health care services after their doctor participated in the Program. The turnover rate was 35.5% for physicians whose participation in the PEP was equal to or greater than 60.0% , whereas for those who do not participate effectively in the Program the turnover rate was 60.9%. It is therefore concluded that permanent education, along the lines of the Permanent Education Program, can improve the clinical performance of the physicians and make users more involved in their treatment. Furthermore, it contributes to retaining professionals in the region.

This master thesis is a result of the work carried out for Research Electronics at Siljansnäs. The company develops customized electronical systems. Because of the rapidly increasing interest in colour displays there has been a desire within the company to represent information from sensors and electrical systems in a more advanced way. Due to the mentioned reason above we were given the assignment to solve how a colour display using the STN technique works. The technique is used by small displays, the size of QVGA. Our ambition of this diploma work is to develop a fully functionally test prototype to evaluate the LCD (Liquid Crystal Display) and the LCD controller. The most important results from this study is the documentation of how a LCD controller works and how the pixels are addressed. We succeded in showing all the pixels we were able to address at the right place on the LCD wich indicates that there is a compatibility between the LCD and the LCD controller . A replacement of the LCD is recommended because of the difficulties working with it. Precisely wich LCD it should be replaced with is not mentioned in this report because of the extent of the work. One of the aims was to evaluate the function of the LCD, not to find an alternative LCD.When studiyng the LPC2129 and MC68K it emerged that both suits well as controlling units for this application, but an implemention with LPC2129 involves greater diffculties because of the absence of external system bus. Our aim is that this work will function as a starting point to further development leading to a controlling unit in working order, and that it will be implemented in other products the company develops. / Föreliggande rapport behandlar vårt magisterarbete på 20 poäng. Arbetet är gjort åt Research Electronics i Siljansnäs som utvecklar skräddarsydda elektroniksystem. På grund av den ökade efterfrågan av färgdisplayer från marknaden har det länge funnits ett behov av att presentera information från givare och mätinstrument på ett mer avancerat sätt. Av ovan nämnda skäl fick vi i uppdrag att undersöka hur en färgdisplay av typen STN (Super Twist Nematic) fungerar. Det är oftast små displayer som använder den här tekniken. Målet från början var att utveckla en fungerande testprototyp för att testa grafikcontrollern och displayen. De viktigaste resultat som framkommit efter arbetet är en dokumentation på hur en grafikcontroller fungerar och hur adressering av pixlar sker. Vi har visat att det är möjligt att använda den givna grafikcontrollern tillsammans med den display som köpts in då alla pixlar som gick att adressera visats på önskad plats på skärmen. Det finns också en rekommendation av byte till en annan display som är enklare att arbeta med. Exakt vilken anges inte i rapporten eftersom det inte har ingått i arbetet att ta hitta en alternativ display utan att undersöka den befintliga. Studien av mikrocontrollern LPC2129 från Philips och processorn MC68K från Freescale visar att båda är bra för applikationen. LPC2129 blir svårare att arbeta med till följd av att det saknas extern systembuss. Våra förhoppningar är att examensarbetet ska bli en god grund för fortsatt arbete som leder till en färdig produkt, och att den används i övriga tillämpningar i företaget.

Positioning information for drones, machines, or other equipment has always been valuable. With fifth generation (5G) and long-term evolution (LTE) there are new possibilities to provide positioning information using the cellular network. When positioning information is available through the cellular network, having a standardized way of exposing positioning information would benefit a various number of applications. Thus, determining what requirements such an application programming interface (API) should have is important for future work. This thesis investigates and analyzes requirements that every API for exposing positioning information must have. It provides a theoretical reference API, the positioning exposure protocol (PEP), that fulfill all requirements. Additionally, the thesis analyzes available APIs on the market, and compares each and every one of them against the PEP, constructing a list of changes and extensions to make them compliant. The most compliant and suitable API is the gateway mobile location center (GMLC) API, which only requires a few changes and extensions to be functionally equivalent and fulfill allrequirements.

Die Regulation des Kohlenstoffkatabolismus erfolgt in Escherichia coli wesentlich über den Einfluss der intrazellulären cAMP-Konzentration auf die Expression der Gene des crpA-Modulon. cAMP wird durch die Adenylatzyklase CyaA synthetisiert, die wiederum durch phosphoryliertes IIACrr aktiviert wird. Im Rahmen eines Stoffwechselmodellierungsprojektes sollten durch die Entwicklung von Systemen zur quantitativen Messung der intrazellulären cAMP-Konzentration und des Phosphorylierungszustands von IIACrr zwei entscheidende Parameter dieses Regulationsnetzwerkes untersucht werden. Zu diesem Zweck wurde ein System zur reproduzierbaren, direkten Messung der intrazellulären cAMP-Konzentration in E. coli etabliert. Zur in vivo Bestimmung der intrazellulären cAMP-Konzentration wurden zwei verschiedene durch cAMP·CrpA regulierte Promotoren mit den Reportergenen für ß-Galaktosidase oder Aequorin (grün fluoreszierendes Protein) fusioniert und in drei verschiedenen Messkonstrukten untersucht. Die Zugabe von Pyruvat zu gehungerten Zellen führte zu einer Desphosphorylierung von IIACrr. Der so direkt gezeigte Einfluss des PEP/Pyruvat Verhältnisses auf das Phosphorylierungsgleichgewicht von IIACrr zeigt einen Mechanismus, über den PTS-unabhängige Substrate den Phosphorylierungszustand von IIACrr verändern und somit die Aktivität der Adenylatzyklase beeinflussen können. Bei der Untersuchung zur zellulären Lokalisation der Adenylatzyklase in E. coli mit Hilfe einer CyaA-Aequorin-Fusion wurde nach Überexpression des Fusionsproteins eine lokale Anhäufung der Fluoreszenz an den Zellpolen beobachtet. Da bei geringerer Expression der Fusion kein Fluoreszenzsignal mehr erfasst werden konnte, war eine endgültige Lokalisierung der Adenylatzklase mit dieser Methode nicht möglich.

The Teen Prevention Education Program (PEP) utilizes different methods, mainly peer teaching via skits and small groups, to help influence adolescents to make informed sexual decisions. The purpose of this study is to find how Teen PEP can have an effect on an adolescent's decision on whether to or not hookup. This study utilized interviews with participants of the program asking them about their views on hooking up and how they view how Teen PEP aided in their decision-making whether to or not hook up. While transcribing the interviews and looking for keywords related to the research questions, the analysis found that out of the 9 interviews performed only one participant had hooked up and that that Teen PEP had influenced their sexual decisions in the future. Another result of the study showed that faith and morality played a part in a participant's decision to not hookup. Some recommendations would be make the scope of the study larger and interview more Teen PEP participants. This study benefits the Teen PEP organization and any high schools that are looking to institute a peer taught sexual education program since the study shows that Teen PEP is an effective program. By showing the efficacy of Teen PEP, that could lead to social change by causing more high schools to implement Teen PEP in order to institute an effective program for sexual education.

Phosphoenolpyruvate carboxykinase (PEPCK) and phosphoenolpyruvate carboxylase (Pepc) are two important CO₂-fixation enzymes which share a similar reaction mechanism. Both operate through a lid-gated active site and have a hypothesized enol-pyruvate intermediate in their catalytic pathway. While PEPCK is an important metabolic enzyme in animals and plays a broad role in cataplerosis, gluconeogenesis and glyceroneogenesis, Pepc reaction in plants catalyzes the first committed step in CO₂ fixation in CAM and C₄ plants via Rubisco. We are studying the structure-function aspects of both enzymes, with a goal of discovering new elements in these enzymes which can modulate catalysis. We have undertaken an interdisciplinary approach for this work and have shown that a combination of experimental and computational techniques can be complementary and can provide novel information. We have determined that in human PEPCK, Tyr235 forms an anion-quadrupole interaction with the carboxylate of PEP and thus positions the latter with respect to the enzyme-bound Mn²+ for optimal phosphoryl transfer and catalysis. We have also identified Pro82 as a catalytically influential residue in this enzyme. Using molecular dynamics simulations we have noted that absence of ligands induces active-site lid opening in GTP-PEPCKS and we have made the first observation of the intermediary structures of the lid opening event, the dynamics of which is an important element that controls GTP-PEPCK catalysis. We have determined the first three-dimensional crystal structure of an archaeal-type Pepc, i.e. C. perfringens PepcA. Our experimental data also provide information about the oligomerization of PepcAs and reveal that aspartate inhibits the C. perfringens enzyme competitively compared to the allosteric inhibition in Pepcs. Structure-based modeling has led to the identification of putative aspartate- and bicarbonate-binding residues in C. perfringens PepcA, of which Arg82, His11, Ser201, Arg390, Lys340, Arg342 and Arg344 probably play an important role. / Ph. D.

Made available in DSpace on 2017-07-10T18:33:33Z (GMT). No. of bitstreams: 1 Dissertacao Salete Polonia Borilli.pdf: 961192 bytes, checksum: 1481efd9b520753fbb339f4168f11673 (MD5) Previous issue date: 2005-12-05 / The objective of this work consists of an analysis of the economic crime of Paraná State through a case study developed in the Central (PCP), Feminine (PFP) and State (PEP) Penitentiaries in the city of Piraquara, based on a primary data collected from questionnaires/interviews which were applied to previously judged and condemned defendants for economic crimes. In this research, the hypothesis that the criminals migration to illegal activities was in the hope of earning more than the risks of the activity was not rejected. The option for the practice of crime of economic nature is a rational and individual one, with or without the influence of others, in face of the perception of costs and benefits such as those made by individuals in relation to others decisions of economic nature. The offenders make individual decisions when the results of criminal action fulfill their interest well or better than the collective action. The relation crime-unemployment did not prove to be so strong in this research, since the majority of the respondents were working when the practice of crime happened. The association of criminality with low level of education was confirmed; the majority of respondents have got only Educação Fundamental (first to four grades), what suggests that high levels of education and better jobs (well payment) can restrict or to retrain the criminality. We observed that more audacious criminal practices besides high levels of organization and planning are essential requisites to these tasks. The principal crime realized were: robbery deal in drugs, fraud, armed-robbery, abduction and extortion that the majority were realized by white young men from the State of Paraná, member of a religious community and having a family. The choice of the type of crime to be realized and the victims, was determined in function of material interest and possible earnings. The main personal motivation to act illegally vis-à-vis to legal was: the induction of friends, the greediness, to maintain the vice, the inconsequence and the wish of adventure, the difficult of money and the idea of easy earnings. The main factors of failure were: the informer, the police's action and their own failure; though, the failure do not refer to the punishment, but to the economic gains not reached. The research revealed that for most of respondents the illegal activity results in some degree of success and for a significant number the economic return was the expected, what justify the great number of relapsing. Finally, for the majority of them the Justice System was considered as insufficient to impede the criminal activity. / O objetivo deste trabalho consiste na análise do crime econômico no Paraná por meio de um estudo de caso nas Penitenciárias Central de Piraquara (PCP), Estadual de Piraquara (PEP) e Feminina de Piraquara (PFP), a partir de dados primários obtidos via aplicação de questionários/entrevistas a réus já julgados e condenados por crimes econômicos. Como corolário deste estudo, não se rejeitou a hipótese de que os criminosos migraram para as atividades ilegais na esperança de os ganhos esperados superassem os riscos da atividade. A opção pela prática do crime de natureza econômica é uma decisão individual tomada racionalmente, com ou sem influências de terceiros, em face da percepção de custos e benefícios, assim como os indivíduos fazem em relação a outras decisões de natureza econômica. Os criminosos agem individualmente quando os resultados da ação criminosa servem aos seus interesses tão bem, ou melhor, que a ação coletiva. A relação crime-desemprego não se constatou tão fortemente neste estudo, pois a maioria dos entrevistados estava trabalhando na época da prática do crime. A associação da criminalidade com o baixo nível de escolaridade foi confirmada, porquanto a maioria dos entrevistados possuía até o 1o grau, o que sugere que maiores níveis educacionais e melhores empregos (com maiores remunerações) podem vir a coibir e/ou tolher a criminalidade. Observou-se que práticas criminosas mais audaciosas e com maior nível de organização e planejamento fazem da educação um requisito essencial para execução de suas tarefas. Os principais crimes econômicos cometidos foram: roubo, latrocínio, tráfico de drogas, furto, estelionato, seqüestro e extorsão, concentrados na sua maioria nos homens brancos, paranaenses, jovens, tendo religião e família. A escolha do tipo de crime a ser praticado, bem como suas vítimas, foi determinado em função do interesse material e da possível renda auferida. Os fatores motivacionais que levaram o indivíduo a atuar no setor ilegal vis-à-vis o setor legal foram: a indução de "amigos", a cobiça/ambição/ganância, manter o sustento do vício, a inconseqüência e desejo de aventura, a dificuldade financeira e a idéia do ganho fácil. Os principais fatores que levaram ao insucesso foram: o dedo-duro (alcagüete), a ação da polícia e a falha própria - descuido, contudo o insucesso citado não se refere à punibilidade, e sim ao retorno econômico não alcançado. A pesquisa revelou que para a maioria dos entrevistados a atividade ilegal resultou em algum grau de sucesso e para um número significativo o retorno econômico foi o esperado, o que justifica o alto índice de reincidentes. Finalmente, o Sistema de Justiça foi considerado, pela maioria, como ineficiente para coibir a atividade criminosa.

Le mode vie autotrophique des plantes repose entièrement sur l’intégrité du chloroplaste et notamment l’étape de la biogénèse. La transcription des gènes chloroplastiques, assurée par une PEP (ARN polymérase encodée par le chloroplaste) et deux NEPs (ARN polymérase encodée par le noyau), est l’une des étapes primordiales dans le développement d’un chloroplaste photosynthétique. On distingue trois classes de gènes chloroplastiques : les gènes de classe I, transcrit par la PEP exclusivement; les gènes de classe II, transcrits par la PEP ou les NEPs; et les gènes de classe III, transcrits exclusivement par les NEPs. Pour assurer sa fonction, la PEP doit être associée à des facteurs sigmas. L’un de ceux-ci, la protéine SIG6, est un facteur sigma général et, associé à la PEP, assure la transcription de l’ensemble des gènes de classe I et II lors du développement du chloroplaste photosynthétique. Ainsi, le mutant sig6 présente un phénotype de cotylédons pâles, associé à un retard de biogénèse chloroplastique, ainsi qu’une diminution de la transcription des gènes de classe I, provoquant la diminution de la quantité de protéines de classe I. Dans le laboratoire, nous étudions les deux protéines WHIRLY chloroplastiques (WHY1 et WHY3) pour leur rôle dans le maintien de la stabilité génomique chloroplastique. Toutefois, peu de choses sont encore connues sur leur rôle potentiel dans la transcription ou la biogénèse chloroplastique. Par exemple, lorsque l’on tente de purifier la PEP, on obtient un gros complexe transcriptionnel nommé PTAC (Plastid Transcriptionally Active Chromosome) dans lequel sont retrouvées les deux protéines WHIRLY, suggérant qu’elles pourraient être impliquées dans la transcription chloroplastique. De plus, un possible rôle dans la biogénèse chloroplastique leur a été prêté, notamment chez le maïs. Dans cette étude, nous avons donc cherché à vérifier l’implication des protéines WHIRLY dans la biogénèse chloroplastique par une approche génétique de croisements entre les mutants sig6 et why1why3. Pour cela, nous avons isolé des doubles mutants sig6why1 et sig6why3, ainsi qu’un triple mutant sig6why1why3. À l’aide d’une caractérisation phénotypique et de la quantification de quelques protéines chloroplastiques, nous avons remarqué que la perte d’un des WHIRLY permet de complémenter le phénotype de cotylédons pâles du mutant sig6 et favorise l’expression normale de protéines en principe sous-exprimées dans le mutant sig6. Toutefois, la perte des deux WHIRLY ne permet pas de compenser le phénotype de cotylédons pâles et provoque l’apparition d’un phénotype persistant associé à une expression anormale des protéines chloroplastiques. Ces résultats ne peuvent être expliqués par le rôle des WHIRLY dans le maintien de la stabilité génomique chloroplastique étant donné que le triple mutant sig6why1why3 présente moins de réarrangements que le double mutant why1why3. Finalement, nous montrons que les effets de la perte d’un WHIRLY sur le mutant sig6 peuvent être mimés par l’utilisation de la rifampicine, une drogue inhibant l’ARN polymérase chloroplastique de type bactérienne (PEP). Ensemble, ces résultats démontrent donc l’implication des protéines WHIRLY chloroplastiques dans la biogénèse chloroplastique en association avec la protéine SIG6. Nous proposons un modèle selon lequel les deux protéines WHIRLY permettraient de favoriser l’activité de l’ARN polymérase de type bactérienne, notamment lors du développement du chloroplaste photosynthétique. En cas d’absence d’une des deux protéines, cette diminution partielle d’activité de la PEP favoriserait la mise en place d’un mécanisme de complémentation par le NEPs, permettant finalement de rétablir la biogénèse chloroplastique dans un mutant sig6. En l’absence des deux WHIRLY, le mécanisme de complémentation par les NEPs serait incapable de compenser la forte inhibition de la PEP, se traduisant par une aggravation du retard de développement du chloroplaste dans le mutant sig6. / The autotrophic lifestyle of plants relies entirely on the integrity of chloroplasts and particularly on their biogenesis. Chloroplast gene transcription, performed by a Plastid-Encoded Polymerase (PEP) and two Nuclear-Encoded Polymerases (NEPs), is one of the key steps during the development of photosynthetic chloroplast. There are 3 classes of genes, one transcribed by PEP alone (class I), one by both PEP and NEPs (class II), and the third by NEPs alone (class III). To carry out transcription, PEP associates with plastid sigma factors including the general sigma factor SIG6. sig6 mutants have a pale cotyledon phenotype, a severe decrease in class I gene transcription and a reduction in the level of class I proteins. In our laboratory, we study the role of the two plastid WIHRLY proteins (WHY1 and WHY3) in maintaining plastid genome stability. However, little is known about any role these proteins may play in transcription or chloroplast biogenesis. It seems likely they are involved in plastid gene transcription since they are found in the Plastid Transcriptionally Active Chromosome (PTAC). Moreover, they have been implicated in chloroplast biogenesis in maize. In this study, we verified the implication of these proteins in plastid biogenesis using a genetic approach in which we crossed a sig6 mutant with a why1why3 mutant. We isolated sig6why1 and sig6why3 double mutants and a sig6why1why3 triple mutant. Using a phenotypic characterisation and quantification of some plastid proteins, we show that loss of one of the two Why genes complements the sig6 pale cotyledon phenotype and allows a more normal pattern of expression of plastid proteins that are under-expressed in the sig6 mutant. However, we also show that loss of the two Why genes does not alleviate the sig6 phenotype. Moreover, the triple mutant shows a second pale phenotype on true leaves, and the plastid protein expression pattern is abnormal compared to either sig6 or wild type plants. Those results cannot be explained by the role of WHIRLY proteins in plastid genome stability since the triple mutant shows fewer plastid genome rearrangements than the why1why3 mutant. Finally, we show that inhibition of the PEP polymerase using rifampicin elicits the same complementation of the sig6 phenotype as the loss of one of the two WHIRLY. Together, these results show the implication of WHIRLY proteins in plastid biogenesis in association with SIG6. We propose a model in which WHIRLY act as activators of PEP activity, particularly during the chloroplast biogenesis. Therefore, the absence of one of the WHIRLY would cause a weak inhibition of PEP, facilitating the set-up of a rescue mechanism by NEPs and, consequently, allowing the complementation of plastid biogenesis in the sig6 mutant. However, the absence of the two WHIRLY proteins would cause a strong inhibition of PEP, and the inability of the rescue mechanism by NEPs to compensate for this strong inhibition, resulting in a more severe phenotype in the sig6 mutant.