A febre reumática é um bom exemplo de uma doença auto-imune deflagrada por um processo infeccioso. Num prazo de uma a quatro semanas após a resolução de uma faringite não tratada por cepas reumatogênicas de S. pyogenes, o organismo de um hospedeiro susceptível desencadeia uma resposta imune contra grandes articulações, coração, tecidos subcutâneos e cérebro. Acredita-se que elementos presentes na bactéria e reconhecidos durante a infecção na orofaringe, sejam confundidos com estruturas próprias do organismo, num processo denominado mimetismo molecular. Entre as proteínas envolvidas na reação cruzada, encontram-se a miosina cardíaca, pelo lado do hospedeiro, e a proteína M do microorganismo invasor. Esta última (proteína M) tem sido extensamente estudad. É a base da classificação das cepas de S. pyogenes e importante fator de virulência. Também tem sido explorada como imunógeno em várias estratégias vacinais. O estudo desta patologia tem sido dificultado pela ausência de um modelo animal que reproduza aspectos fundamentais da patologia humana, entre estes as lesões cardíacas. Uma das razões é o fato de que animais não contraem infecção pelo S. pyogenes. Portanto, produzimos a proteína M1 recombinante e mostramos que a imunização de 28 ratos Lewis por um período de 21 dias ou 14 ratos por 41 dias, com esta proteína foi capaz de induzir resposta inflamatória na maioria dos animais com intensidade variável. Células similares aos nódulos de Aschoff e células de Anitschkow, sugestivas das lesões patognomônicas da febre reumática foram observadas em dias e também de um em quatro dos animais controles que receberam PBS e adjuvantes. Estes resultados sugerem a presença de células auto-reativas no miocárdio dos animais imunizados. Em conclusão, o uso de proteína M1 recombinante como imunógeno em modelo animal de ratos Lewis é capaz de desencadear reação inflamatória em miocárdio e tecido valvular e lesões similares às da febre reumática. O modelo do rato Lewis é até o momento o que apresenta maior semelhança com a doença humana e pode ajudar a esclarecer a imunopatologia da febre reumática. Além disso, certamente será importante para a avaliação do potencial de proteção e de segurança em modelos de vacinas contra o S. pyogenes. / Rheumatic fever is a good example of an autoimmune disease triggered by an infectious process. One to four weeks after the resolution of a non treated pharyngitis caused by rheumatogenic strains of S. pyogenes, the susceptible host unravels an immune response targeting joints, heart, conective tissues and brain. It is thought that molecules present in the bacteria and recognized during the infection at the pharynx are confounded with the organism self structure in a process called ?molecular mimicry?. Amongst the proteins involved in the cross reaction, it may be found cardiac myosin, on the host side, and M protein on the invading organism?s side. The latter (Mprotein) has been extensively studied. It is the basis of the S. pyogenes strains classification, and also an important virulence factor. It has also been explored as an immunogen in several vaccine strategies. The nderstanding of this disease has been hampered by the absence of an animal model that reproduces fundamental aspects of the human pathology, specially cardiac lesions. One of the reasons is the fact that animals do not get infected by S. pyogenes. Hence we have produced the recombinant M1 protein and shown that either the immunization of 28 Lewis rats for a period of 21 days or 14 rats for a period of 41 days, was capable of inducing an inflammatory response in most of the animals with variable intensity. Aschoff nodules-like or Anitschkow-like cells resembling rheumatic fever pathognomonic lesions were seen in 50% of the animals immunized subcutaneously and sacrificed on day 21. We have observed an humoral and cellular response (spleen and lymph node derived cells) specifically targeting M1 protein and the amino (M1AB) and carboxy (M1C) terminus of the protein. However, cross reactions with cardiac myosin were not observer. We have derived T lymphocyte lineages obtained from myocardium infiltrating mononuclear cells from 6 of the 10 animals immunized with M1ABC protein subcutaneously and sacrificed on day 41 and also from one out of four PBS - adjuvant immunized animals. These results suggest the presence of autoreactive cells in the myocardium of the immunized animals. In conclusion, the use of the M1 protein as an immunogen on the Lewis rat model is capable of triggering an inflammatory reaction in the myocardium and valvular tissue and it can produce rheumatic fever like lesions. The Lewis rat model is up to this moment the one to present the highest similarity with human disease. Besides, it will certainly be important on the evaluation of the protection and safety of S. pyogenes vaccines.

O Streptococcus pyogenes (Grupo A de Lancefield) é uma bactéria Gram positiva e beta-hemolítica, responsável por infecções, tais como Faringite, Sepse, Fasciíte Necrotizante e Síndrome do Choque Tóxico Estreptocócico. Indivíduos suscetíveis podem desenvolver sequela não supurativa auto-imune pós-estreptocócica, como a Febre Reumática, Doença Reumática Cardíaca e a Glomerulonefrite Aguda. A proteína M é o principal antígeno bacteriano. Consiste em aproximadamente 450 resíduos de aminoácidos dispostos em quatro regiões (A, B, C e D), contendo alguns blocos de repetições. As regiões C e D são conservadas e a N-terminal (regiões A e B) é polimórfica. Atualmente, existem mais de 250 genótipos de emm conhecidos em todo o mundo, de acordo com o Centers for Disease Control and Prevention. Há vários anos, o desenvolvimento de uma vacina contra S. pyogenes (StreptInCor - identificação médica) foi iniciado, com base na região conservada da proteína M, com o objetivo de proteger o indivíduo vacinado contra infecções estreptocócicas, sem causar reações autoimunes. No presente estudo foi analisada a capacidade \"in vitro\" de anticorpos anti-StreptInCor neutralizarem/opsonizarem as cepas de S. pyogenes mais freqüentes em São Paulo, através da análise do reconhecimento das cepas por soros de camundongos imunizados com StreptInCor. Também foi avaliada por Western blotting a presença de anticorpos de reação cruzada dirigidos ao tecido cardíaco valvular humano. Anticorpos anti-StreptInCor foram capazes de neutralizar/opsonizar, pelo menos, cinco diferentes cepas mostrando que a imunização com StreptInCor pode ser eficaz contra várias cepas de S. pyogenes, assim como prevenir a infecção e sequelas subsequentes, sem causar reações auto-imunes. / Streptococcus pyogenes (Group A) is a Gram positive and beta-hemolytic bacteria, responsible for infections such as Pharyngitis, Sepsis, Necrotizing Fasciitis and Streptococcal Toxic Shock Syndrome. Susceptible individuals may develop post-streptococcal non-suppurative autoimmune sequelae such as Rheumatic Fever, Rheumatic Heart Disease and Acute Glomerulonephritis. The M protein is the major bacterial antigen. It consists of approximately 450 amino acid residues arranged in four regions (A, B, C and D), containing some repeated blocks. C and D regions are conserved and the N-terminus (regions A and B) is polymorphic. Currently there are over 250 known emm genotypes worldwide, according to the Centers for Disease Control and Prevention. Several years ago the development of a vaccine against S. pyogenes (StreptInCor - medical identification) was initiated, based on the M protein conserved region, aiming to protect against streptococcal infections without causing autoimmune reactions. In the present study we analyzed the \"in vitro\" ability of anti-StreptInCor antibodies to neutralize/opsonize the most frequent S. pyogenes strains in Sao Paulo by examining the strains recognition by sera from StreptInCor immunized mice. We also evaluated the presence of cross reactive antibodies directed to the human heart valve tissue by Western blotting. Anti-StreptInCor antibodies were able to neutralize/opsonize at least 5 strains, showing that the immunization with StreptInCor can be effective against several S. pyogenes strains as well as preventing infection and subsequent sequelae, without causing autoimmune reactions.

INTRODUÇÃO: A Faringotonsilite é doença comum nos consultórios e prontosocorros de pediatria. OBJETIVOS: Avaliar o impacto da realização rotineira da prova rápida para pesquisa de estreptococo do grupo A (PRE) no diagnóstico e tratamento da faringotonsilite aguda em crianças e adolescentes atendidos em um Hospital Geral. MÉTODOS: Trata-se de um estudo prospectivo, observacional, de protocolo de atendimento, instituído no Pronto-Socorro do Hospital Universitário da Universidade de São Paulo para o atendimento de crianças e adolescentes com diagnóstico de faringotonsilite aguda. RESULTADOS: Foram estudadas 1039 crianças e adolescentes. Com base no quadro clínico, antibiótico seria prescrito em 530 pacientes (51%), e com o uso da PRE e/ou cultura de orofaringe foi prescrito em 268 (25,8%) pacientes. Das 509 crianças que não receberiam antibiótico pelo quadro clínico, 157 tiveram PRE e/ou cultura de orofaringe positiva. O diagnóstico baseado no quadro clínico apresentou sensibilidade de 63,06% (IC-95%:62,95-63,17%); especificidade de 57,33% (IC-95%:57,25-57,41%); valor preditivo positivo de 50,57% (IC-95%:50,47-50,66%) e valor preditivo negativo de 69,16% (IC-95%: 50,47-50,66%). CONCLUSÕES: Neste estudo o diagnóstico clínico da faringotonsilite estreptocócica mostrou baixa sensibilidade e especificidade. O uso rotineiro da prova rápida para pesquisa de estreptococo permitiu uma redução do uso de antibiótico e a identificação de crianças e adolescentes com faringotonsilite estreptocócicas que não receberiam antibiótico e estariam sob o risco das complicações da infecção estreptocócica / BACKGROUND: Sore throat is a common disease in the pediatric emergency room. OBJECTIVES: The objective of this study was to evaluate the impact of routine performance of rapid antigen detection test (RADT) in the diagnosis and treatment of acute pharyngitis in children treated at an academic hospital. METHODS: This is a prospective, observational, protocol compliance, established at the Emergency of Hospital Universitário - Universidade de São Paulo for the care of children and adolescents diagnosed with acute pharyngitis. RESULTS: We studied 1039 children and adolescents. Based on clinical findings, antibiotic would be prescribed in 530 patients (51%) and using the RADT or sore throat culture was prescribed in 268 patients. Of the 509 children who did not receive antibiotics for the clinical, 157 had positive RADT or sore throat culture. The diagnosis based on clinical sensitivity was 63,06% (IC 95% 62,95- 63,17%), specificity 57,3% (IC 95% 57,25-57,41%), positive predictive value of 50,57% (IC 95% 50,47-50,66%) and negative predictive value of 69,16% (IC 95% 50,47-50,66%). CONCLUSIONS: In this study the clinical diagnosis of streptococcal pharyngitis had low sensitivity and specificity. The routine use of rapid test for streptococcal research led to a reduction of antibiotic use and the identification of a risk group for complication of streptococcal infection

INTRODUÇÃO: A Faringotonsilite é doença comum nos consultórios e prontosocorros de pediatria. OBJETIVOS: Avaliar o impacto da realização rotineira da prova rápida para pesquisa de estreptococo do grupo A (PRE) no diagnóstico e tratamento da faringotonsilite aguda em crianças e adolescentes atendidos em um Hospital Geral. MÉTODOS: Trata-se de um estudo prospectivo, observacional, de protocolo de atendimento, instituído no Pronto-Socorro do Hospital Universitário da Universidade de São Paulo para o atendimento de crianças e adolescentes com diagnóstico de faringotonsilite aguda. RESULTADOS: Foram estudadas 1039 crianças e adolescentes. Com base no quadro clínico, antibiótico seria prescrito em 530 pacientes (51%), e com o uso da PRE e/ou cultura de orofaringe foi prescrito em 268 (25,8%) pacientes. Das 509 crianças que não receberiam antibiótico pelo quadro clínico, 157 tiveram PRE e/ou cultura de orofaringe positiva. O diagnóstico baseado no quadro clínico apresentou sensibilidade de 63,06% (IC-95%:62,95-63,17%); especificidade de 57,33% (IC-95%:57,25-57,41%); valor preditivo positivo de 50,57% (IC-95%:50,47-50,66%) e valor preditivo negativo de 69,16% (IC-95%: 50,47-50,66%). CONCLUSÕES: Neste estudo o diagnóstico clínico da faringotonsilite estreptocócica mostrou baixa sensibilidade e especificidade. O uso rotineiro da prova rápida para pesquisa de estreptococo permitiu uma redução do uso de antibiótico e a identificação de crianças e adolescentes com faringotonsilite estreptocócicas que não receberiam antibiótico e estariam sob o risco das complicações da infecção estreptocócica / BACKGROUND: Sore throat is a common disease in the pediatric emergency room. OBJECTIVES: The objective of this study was to evaluate the impact of routine performance of rapid antigen detection test (RADT) in the diagnosis and treatment of acute pharyngitis in children treated at an academic hospital. METHODS: This is a prospective, observational, protocol compliance, established at the Emergency of Hospital Universitário - Universidade de São Paulo for the care of children and adolescents diagnosed with acute pharyngitis. RESULTS: We studied 1039 children and adolescents. Based on clinical findings, antibiotic would be prescribed in 530 patients (51%) and using the RADT or sore throat culture was prescribed in 268 patients. Of the 509 children who did not receive antibiotics for the clinical, 157 had positive RADT or sore throat culture. The diagnosis based on clinical sensitivity was 63,06% (IC 95% 62,95- 63,17%), specificity 57,3% (IC 95% 57,25-57,41%), positive predictive value of 50,57% (IC 95% 50,47-50,66%) and negative predictive value of 69,16% (IC 95% 50,47-50,66%). CONCLUSIONS: In this study the clinical diagnosis of streptococcal pharyngitis had low sensitivity and specificity. The routine use of rapid test for streptococcal research led to a reduction of antibiotic use and the identification of a risk group for complication of streptococcal infection

La tagatose-1,6-biphosphate aldolase de Streptococcus pyogenes est une aldolase de classe I qui fait montre d'un remarquable manque de spécificité vis à vis de ses substrats. En effet, elle catalyse le clivage réversible du tagatose-1,6-biphosphate (TBP), mais également du fructose-1,6-biphosphate (FBP), du sorbose-1,6-biphosphate et du psicose-1,6-biphosphate, quatre stéréoisomères, en dihydroxyacétone phosphate (DHAP) et en glycéraldéhyde-3-phosphate (G3P). Afin de mettre à jour les caractéristiques du mécanisme enzymatique, une étude structurale de la TBP aldolase de S. pyogenes, un pathogène humain extrêmement versatile, a été entreprise. Elle a permis la résolution de la structure native et en complexe avec le DHAP, a respectivement 1.87 et 1.92 Å de résolution. Ces mêmes structures ont permis de se représenter plus clairement le site actif de l'enzyme en général, et les résidus catalytiques en particulier. Le trempage des cristaux de TBP aldolase dans une solution saturante de DHAP a en outre permis de piéger un authentique intermédiaire iminium, ainsi que sa géométrie particulière en atteste. Des expériences d'échange de proton, entreprises afin d'évaluer le stéréoisomérisme du transfert de proton catalytique, ont également permis de faire une intéressante découverte : la TBP aldolase ne peut déprotoner le coté pro-R du C3 du DHAP, mais peut le protonner. Ce résultat, ainsi que la comparaison de la structure du complexe TBP aldolase-DHAP avec la structure du complexe FBP aldolase de muscle de lapin- DHAP, pointe vers un isomérisme cis-trans autour du lien C2-C3 de la base de Schiff formée avec le DHAP. De plus, la résolution de ces deux structures a permis de mettre en évidence trois régions très mobiles de la protéine, ce qui pourrait être relié au rôle postulé de son isozyme chez S. pyogenes dans la régulation de l’expression génétique et de la virulence de la bactérie. La cristallographie par rayons X et la cinétique enzymatique ont ainsi permis d'avancer dans l'élucidation du mécanisme et des propriétés structurales de cette enzyme aux caractéristiques particulières. / Tagatose-1,6-biphosphate aldolase from Streptococcus pyogenes is a class I aldolase that shows a lack of stereospecificity that is rare in enzymes in general, and in aldolases in particular. This aldolase catalyzes the reversible cleavage of tagatose-1,6-biphosphate (TBP), fructose-1,6-biphosphate (FBP), sorbose-1,6-biphosphate and psicose-1,6-biphosphate, four stereoisomers, in dihydroxyacetone phosphate and glyceraldehyde-3-phosphate (DHAP). In order to understand its mechanism, a structural study of TBP aldolase from S. pyogenes, one of the most versatile and virulent human pathogen, was initiated and high resolution crystallographic structures of native and DHAP-liganded TBP aldolase were solved. These structures allowed us to gain informations regarding active site residues implicated in catalysis and that give rise to the apparent lack of specificity. Soaking of TBP aldolase crystals in saturating DHAP solution specifically trapped the iminium intermediate, as demonstrated by its geometry. Furthermore, proton transfer studies uncovered an interesting phenomenon: TBP aldolase from S. pyogenes is unable to detritiate pro-R labelled hydrogen position at C3 of DHAP, yet it is able to tritiate both the pro-R and the pro-S position. These results, taken together with the superposition of the DHAP-TBP aldolase with the DHAP-FBP aldolase from rabbit muscle, suggest a cis-trans isomerism about the Schiff base C2-C3 bond. The resolution of both the native and the liganded structure also proved useful in identifying three very mobile regions in the protein. This trend could be linked to the putative metabolic sensor and genetic expression regulator role of LacD.1 in S. pyogenes. X-rays crystallography and traditional enzymatic kinetics allowed us to gain insights into the catalytic mechanism and others structural properties of this important metabolic enzyme.

O Streptococcus pyogenes (Grupo A de Lancefield) é uma bactéria Gram positiva e beta-hemolítica, responsável por infecções, tais como Faringite, Sepse, Fasciíte Necrotizante e Síndrome do Choque Tóxico Estreptocócico. Indivíduos suscetíveis podem desenvolver sequela não supurativa auto-imune pós-estreptocócica, como a Febre Reumática, Doença Reumática Cardíaca e a Glomerulonefrite Aguda. A proteína M é o principal antígeno bacteriano. Consiste em aproximadamente 450 resíduos de aminoácidos dispostos em quatro regiões (A, B, C e D), contendo alguns blocos de repetições. As regiões C e D são conservadas e a N-terminal (regiões A e B) é polimórfica. Atualmente, existem mais de 250 genótipos de emm conhecidos em todo o mundo, de acordo com o Centers for Disease Control and Prevention. Há vários anos, o desenvolvimento de uma vacina contra S. pyogenes (StreptInCor - identificação médica) foi iniciado, com base na região conservada da proteína M, com o objetivo de proteger o indivíduo vacinado contra infecções estreptocócicas, sem causar reações autoimunes. No presente estudo foi analisada a capacidade \"in vitro\" de anticorpos anti-StreptInCor neutralizarem/opsonizarem as cepas de S. pyogenes mais freqüentes em São Paulo, através da análise do reconhecimento das cepas por soros de camundongos imunizados com StreptInCor. Também foi avaliada por Western blotting a presença de anticorpos de reação cruzada dirigidos ao tecido cardíaco valvular humano. Anticorpos anti-StreptInCor foram capazes de neutralizar/opsonizar, pelo menos, cinco diferentes cepas mostrando que a imunização com StreptInCor pode ser eficaz contra várias cepas de S. pyogenes, assim como prevenir a infecção e sequelas subsequentes, sem causar reações auto-imunes. / Streptococcus pyogenes (Group A) is a Gram positive and beta-hemolytic bacteria, responsible for infections such as Pharyngitis, Sepsis, Necrotizing Fasciitis and Streptococcal Toxic Shock Syndrome. Susceptible individuals may develop post-streptococcal non-suppurative autoimmune sequelae such as Rheumatic Fever, Rheumatic Heart Disease and Acute Glomerulonephritis. The M protein is the major bacterial antigen. It consists of approximately 450 amino acid residues arranged in four regions (A, B, C and D), containing some repeated blocks. C and D regions are conserved and the N-terminus (regions A and B) is polymorphic. Currently there are over 250 known emm genotypes worldwide, according to the Centers for Disease Control and Prevention. Several years ago the development of a vaccine against S. pyogenes (StreptInCor - medical identification) was initiated, based on the M protein conserved region, aiming to protect against streptococcal infections without causing autoimmune reactions. In the present study we analyzed the \"in vitro\" ability of anti-StreptInCor antibodies to neutralize/opsonize the most frequent S. pyogenes strains in Sao Paulo by examining the strains recognition by sera from StreptInCor immunized mice. We also evaluated the presence of cross reactive antibodies directed to the human heart valve tissue by Western blotting. Anti-StreptInCor antibodies were able to neutralize/opsonize at least 5 strains, showing that the immunization with StreptInCor can be effective against several S. pyogenes strains as well as preventing infection and subsequent sequelae, without causing autoimmune reactions.

A febre reumática é um bom exemplo de uma doença auto-imune deflagrada por um processo infeccioso. Num prazo de uma a quatro semanas após a resolução de uma faringite não tratada por cepas reumatogênicas de S. pyogenes, o organismo de um hospedeiro susceptível desencadeia uma resposta imune contra grandes articulações, coração, tecidos subcutâneos e cérebro. Acredita-se que elementos presentes na bactéria e reconhecidos durante a infecção na orofaringe, sejam confundidos com estruturas próprias do organismo, num processo denominado mimetismo molecular. Entre as proteínas envolvidas na reação cruzada, encontram-se a miosina cardíaca, pelo lado do hospedeiro, e a proteína M do microorganismo invasor. Esta última (proteína M) tem sido extensamente estudad. É a base da classificação das cepas de S. pyogenes e importante fator de virulência. Também tem sido explorada como imunógeno em várias estratégias vacinais. O estudo desta patologia tem sido dificultado pela ausência de um modelo animal que reproduza aspectos fundamentais da patologia humana, entre estes as lesões cardíacas. Uma das razões é o fato de que animais não contraem infecção pelo S. pyogenes. Portanto, produzimos a proteína M1 recombinante e mostramos que a imunização de 28 ratos Lewis por um período de 21 dias ou 14 ratos por 41 dias, com esta proteína foi capaz de induzir resposta inflamatória na maioria dos animais com intensidade variável. Células similares aos nódulos de Aschoff e células de Anitschkow, sugestivas das lesões patognomônicas da febre reumática foram observadas em dias e também de um em quatro dos animais controles que receberam PBS e adjuvantes. Estes resultados sugerem a presença de células auto-reativas no miocárdio dos animais imunizados. Em conclusão, o uso de proteína M1 recombinante como imunógeno em modelo animal de ratos Lewis é capaz de desencadear reação inflamatória em miocárdio e tecido valvular e lesões similares às da febre reumática. O modelo do rato Lewis é até o momento o que apresenta maior semelhança com a doença humana e pode ajudar a esclarecer a imunopatologia da febre reumática. Além disso, certamente será importante para a avaliação do potencial de proteção e de segurança em modelos de vacinas contra o S. pyogenes. / Rheumatic fever is a good example of an autoimmune disease triggered by an infectious process. One to four weeks after the resolution of a non treated pharyngitis caused by rheumatogenic strains of S. pyogenes, the susceptible host unravels an immune response targeting joints, heart, conective tissues and brain. It is thought that molecules present in the bacteria and recognized during the infection at the pharynx are confounded with the organism self structure in a process called ?molecular mimicry?. Amongst the proteins involved in the cross reaction, it may be found cardiac myosin, on the host side, and M protein on the invading organism?s side. The latter (Mprotein) has been extensively studied. It is the basis of the S. pyogenes strains classification, and also an important virulence factor. It has also been explored as an immunogen in several vaccine strategies. The nderstanding of this disease has been hampered by the absence of an animal model that reproduces fundamental aspects of the human pathology, specially cardiac lesions. One of the reasons is the fact that animals do not get infected by S. pyogenes. Hence we have produced the recombinant M1 protein and shown that either the immunization of 28 Lewis rats for a period of 21 days or 14 rats for a period of 41 days, was capable of inducing an inflammatory response in most of the animals with variable intensity. Aschoff nodules-like or Anitschkow-like cells resembling rheumatic fever pathognomonic lesions were seen in 50% of the animals immunized subcutaneously and sacrificed on day 21. We have observed an humoral and cellular response (spleen and lymph node derived cells) specifically targeting M1 protein and the amino (M1AB) and carboxy (M1C) terminus of the protein. However, cross reactions with cardiac myosin were not observer. We have derived T lymphocyte lineages obtained from myocardium infiltrating mononuclear cells from 6 of the 10 animals immunized with M1ABC protein subcutaneously and sacrificed on day 41 and also from one out of four PBS - adjuvant immunized animals. These results suggest the presence of autoreactive cells in the myocardium of the immunized animals. In conclusion, the use of the M1 protein as an immunogen on the Lewis rat model is capable of triggering an inflammatory reaction in the myocardium and valvular tissue and it can produce rheumatic fever like lesions. The Lewis rat model is up to this moment the one to present the highest similarity with human disease. Besides, it will certainly be important on the evaluation of the protection and safety of S. pyogenes vaccines.

Ziel der Arbeit war es, die regulatorischen Mechanismen von Virulenz-assoziierten Genen in den Pathogenen Francisella novicida und Streptococcus pyogenes zu untersuchen. Kapitel eins befasst sich mit der Regulation des Virulenzfaktors Streptolysin S (SLS) von S. pyogenes. Wir untersuchten die Rolle der Ribonuklease (RNase) Y in der transkriptionellen und posttranstrikptionellen Regulation des Gens sagA. RNase Y begünstigte die Produktion einer kleinen RNA (sRNA) vom sagA Transkript, war jedoch nicht an der posttranskriptionellen Regulierung der sagA RNA beteiligt. Dennoch förderte RNase Y die Transkription von sagA indirekt. Wir konnten weiterhin zeigen, dass die 5′- untranslatierte Region (UTR) der sgaA RNA eine Sekundärstruktur besitzt, die möglicherweise einen Liganden bindet und damit die Zugänglichkeit der ribosomalen Bindungsstelle beeinflusst. Die Deletion einzelner Abschnitte der 5′ UTR hat einen negativen Effekt auf die sagA Expression. Wir haben eine Methode entwickelt um die Aktivität von Riboswitches, (u.a. die sagA 5‘ UTR) zu analysieren und konnten damit drei putative Riboswitches in S. pyogenes validieren. In Kapitel zwei charakterisierten wir den Mechanismus mit dem CRISPR-Cas9 aus F. novicida (FnoCas9) die Expression bakterieller Lipoproteine (BLPs) unterdrückt, um dem Immunsystem des Wirtes zu entgehen. Wir zeigen, dass FnoCas9 eine duale Funktion besitzt, die es dem Protein ermöglicht nicht nur DNA zu schneiden, sondern auch Transkription zu regulieren. In dieser erstmals beschriebenen Aktivität bindet FnoCas9 an den tracrRNA:scaRNA Duplex, wodurch der Protein-RNA Komplex an einen DNA Abschnitt hinter dem Promoter der blp Gene bindet und somit deren Transkription verhindert. Diese Bindungsstelle besitzt ein protospacer-adjacent motif (PAM) und eine scaRNA-komplementäre Sequenz, an die der FnoCas9-RNA Komplex bindet, allerdings nicht schneidet. Dieses System könnte in Zukunft das Repertoire an CRISPR-basierten Anwendungsmöglichkeiten erweitern. / The aim of this thesis was to study regulatory mechanisms of virulence-related genes in the bacterial pathogens Francicella novicida and Streptococcus pyogenes. Chapter one focuses on the regulation of the virulence factor streptolysin S (SLS) in S. pyogenes. First, we investigated the role of the ribonuclease (RNase) Y in the transcriptional and post-transcriptional regulation of SLS-coding gene, sagA. We found that RNase Y promotes the production of a small RNA (sRNA) from the sagA transcript but we observed no regulation at the post-transcriptional level. Yet, RNase Y promotes sagA transcription indirectly and affects hemolysis levels. We next showed that the sagA 5′ untranslated region (UTR) contains a secondary structure that is is possibly modulated by direct binding to a ligand and may affect the accessibility to the ribosomal binding site (RBS). Our results indicate that removing fragments of the 5′ UTR has a negative effect on sagA expression. We developed a method for testing the activity of putative riboswitches, including sagA 5′ UTR. Using this method, we validated three predicted riboswitches in S. pyogenes. In chapter two, we characterized the mechanism by which F. novicida CRISPR-Cas9 (FnoCas9) represses the expression of bacterial lipoproteins (BLPs), allowing evasion of the host immune system. We show that FnoCas9 is a dual-function protein that, in addition to its canonical DNA nuclease activity, evolved the ability to regulate transcription. In this newly-described mechanism, the non-canonical RNA duplex tracrRNA:scaRNA guides FnoCas9 to the DNA target located downstream of the promoter of the BLP-coding genes, causing transcriptional interference. The endogenous targets contain a protospacer-adjacent motif (PAM) and a sequence that is complementary to scaRNA, promoting FnoCas9 binding but not DNA cleavage. Engineering this system expands the toolbox of CRISPR applications by allowing repressing other genes of interest.

Streptococcus pyogenes ist ein humanpathogenes Bakterium, welches verschiedene Gewebe besiedeln kann und dadurch unterschiedliche Krankheiten verursacht. Die enorme Anpassungsfähigkeit des Bakteriums beruht auf dessen Fähigkeit, verschiedene, vom Wirt induzierte Stresskonditionen zu ertragen. Genetische Faktoren, die in diesem Zusammenhang eine Rolle spielen, sind Toxin-Antitoxin (TA) Systeme. Typ II TA Systeme kodieren für zwei Proteine, ein Toxin und ein Antitoxin, die einen stabilen TA Komplex bilden. Verschlechtern sich die Wachstumsbedingungen, kann das Antitoxin proteolytisch abgebaut werden, wodurch das freigesetzte Toxin essentielle zelluläre Prozesse des Bakteriums inhibiert. In dieser Studie charakterisierte ich zwei chromosomal kodierte ParDE TA Systeme des pathogenen Bakteriums S. pyogenes. Ähnlich zu anderen Systemen werden das Toxin und das Antitoxin beider hier charakterisierten Systeme co-transkribiert und durch Stresseinwirkung (z.B. Aminosäure-mangel) induziert. Zudem konnten weitere posttranskriptionelle bzw. posttranslationale Mechanismen zur Regulierung der Genexpression beider Systeme nachgewiesen werden. Die extrachromosomale Expression der Toxine ParE1 und ParE2 führten in S. pyogenes und Escherichia coli zum Zelltod, wobei die Co-expression der entsprechenden Antitoxine ParD1 und ParD2 die Toxizität minderte. Allerdings verursachte die Überexpression der Antitoxine allein ebenfalls eine Inhibierung des Zellwachstums. ParD1 hemmte die Zellteilung in E. coli, wobei der N-Terminus des Proteins entscheidend für diesen Effekt zu sein schien. Zusammengefasst erweitern die Ergebnisse dieser Arbeit unser Verständnis von ParE Toxinen und verdeutlichen die diversen Mechanismen, welcher sich TA Systeme bedienen, um die bakterielle Physiologie zu beeinflussen. Zusätzlich gibt diese Arbeit einen Einblick in mögliche Mechanismen, die S. pyogenes implementiert, um Stresskonditionen im Wirt zu überdauern. / Streptococcus pyogenes is a human pathogen with a remarkable ability to colonize different tissues and to endure diverse host-induced stress conditions through mechanisms that have yet to be fully understood. One strategy employed by bacteria to cope with changing environments are toxin-antitoxin (TA) genetic modules. Under non-ideal conditions, the antitoxin is subject to proteolysis and thus the freed toxin protein can target crucial pathways in the cell modulating bacterial growth. This study, describes the characterization of two chromosomally encoded ParDE-like TA systems from the human pathogen S. pyogenes. The antitoxin-toxin genes of the parDEF1 and parDE2 TA systems are co-transcribed and triggered by stress-induced conditions. The parDE2 TA showed an inspected mRNA processing under amino acid starvation which suggest a putative post-transcriptional regulation. At the post-translational level, both systems are controlled by ClpXP antitoxin-protein degradation in vivo, an important factor for TA triggering. Furthermore, bacterial plasmid-based expression of the toxins ParE1 and ParE2 resulted in effects in cell viability while the antitoxin molecules ParD1 and ParD2 were able to prevent the toxins lethality, respectably. Unlike canonical antitoxins, both ParD1 and ParD2 molecules also displayed deleterious effects, which seemed to be exclusive and related with the N-terminus domain potentially involved in DNA-interaction. Finally, the ParE toxins presented remarkable plasticity, able to harm not only gyrase but also topoisomerase IV, two important bacterial drug targets that modulate DNA-topology. These results expand the view on the ParE molecular targets and highlight the diverse mechanisms TAs employ to modulate bacterial physiology. We also provide more insights into possible mechanisms that S. pyogenes employs to endure stress in the host and efficiently cause disease.

Bakterien haben eine Vielzahl an Strategien entwickelt, um sich an ständig wechselnde Umweltbedingungen anzupassen, darunter auch post-transkriptionelle regulatorische Mechanismen. Die Genexpression kann hierbei durch gezielten Abbau oder Stabilisierung von RNA durch Ribonukleasen (RNasen) reguliert werden. RNasen weisen je nach Spezies allerdings unterschiedliche Effekte auf Genexpression und bakterielle Physiologie, sowie verschiedene Strategien der Substraterkennung auf. Dies zeigt, dass unser Verständnis des RNA-Abbaus bei weitem nicht vollständig ist. Ziel dieser Arbeit ist es, die Eigenschaften und Funktionen der endoRNase Y des humanpathogenen Bakteriums Streptococcus pyogenes zu studieren. Um Einblick in Funktion und Spezifität dieser RNase zu gewinnen, wurden deren genomweite Schnittpositionen (“targetome”) mit Hilfe von RNA-Sequenzierung identifiziert. Zur weiteren Analyse des RNase Y-abhängigen RNA-Abbaus wurde dieses Ergebnis mit dem “targetome” der drei 3′-5′-Exoribonukleasen (ExoRNasen) PNPase, YhaM und RNase R verglichen. Schließlich wurden die Anforderungen für die Prozessierung durch RNase Y und deren Rolle in der Regulation von Virulenzgenen in vivo anhand der speB mRNA, die einen wichtigen Virulenzfaktor codiert, untersucht. Wir konnten in dieser Arbeit zeigen, dass RNase Y Substrate bevorzugt nach einem Guanosin schneidet und dieses Nukleosid essenziell für die Prozessierung der speB mRNA in vivo ist. Obwohl RNase Y die speB mRNA schneidet, unterstützen die Daten ein Modell nach dem RNase Y die Expression von speB auf transkriptioneller Ebene reguliert. Mit Hilfe des “targetome”-Vergleichs konnten wir ferner zeigen, dass RNase Y den RNA-Abbau in S. pyogenes initiiert und die dabei generierten 3′-Enden der RNA hauptsächlich von den 3′-5′-exoRNasen PNPase und/oder YhaM prozessiert werden. Zusammenfassend erweitern diese Erkenntnisse unser Verständnis der Funktionalität von RNase Y und des RNA-Abbaus in Gram-positiven Bakterien. / Bacteria have developed a plethora of strategies to cope with constantly changing environmental conditions, including post-transcriptional regulatory mechanisms. With this regard, regulation of gene expression can be achieved by either the rapid removal or stabilization of RNA molecules by ribonucleases (RNases). RNases exhibit species-specific effects on gene expression, bacterial physiology and different strategies of target recognition, indicating that our understanding of the RNA degradation machinery is not yet complete. The aim of this thesis was to investigate the features and functions of endoRNase Y from the strict human pathogen Streptococcus pyogenes. To gain insight into the role and specificity of this RNase, we identified RNase Y cleavage positions (i.e. targetome) genome-wide by RNA sequencing. Next, to investigate the RNA degradation pathway depending on RNase Y, we compared the RNase Y targetome with the ones of the three 3′-to-5′ exoribonuclease (exoRNases), namely PNPase, YhaM and RNase R. Finally, to dissect the requirements for RNase Y processing and to decipher the role of RNase Y in virulence gene regulation, we studied the impact of RNase Y on speB mRNA, encoding a major virulence factor. This study reveals that RNase Y preferentially cleaves RNAs downstream of a guanosine and for the first time we were able to show that the presence of a guanosine residue is essential for the processing of speB mRNA, in vivo. Although RNase Y cleaves the speB mRNA, our data underpin a model in which RNase Y-mediated regulation of speB expression occurs at the transcriptional level. Using the targetome comparative approach, we demonstrated that RNase Y initiates RNA decay in S. pyogenes and that the RNase Y-generated RNA 3′ ends are usually further trimmed by PNPase and/or YhaM. Overall, these findings increase our understanding of RNase Y functionality and RNA degradation in Gram-positive bacteria.