Novos inibidores peptídicos de topoisomerases bacterianas estruturalmente derivados da proteína CcdB
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Data
2007-09-20
Autores
Garrido, Saulo Santesso [UNESP]
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Editor
Universidade Estadual Paulista (Unesp)
Resumo
A maioria das bactérias possui dois tipos de topoisomerases IIA, DNA girase e topoisomerase IV (topo IV), que juntas ajudam a administrar a integridade e a topologia do DNA. A girase primariamente introduz superenovelamento negativo no DNA, e a topo IV, embora intimamente relacionada com a girase, preferencialmente desencadeia o DNA plasmidial e relaxa o superenovelamento positivo, funções essenciais para a replicação do DNA e transcrição. Isso faz da girase e da topo IV alvos importantes para diversas drogas antibacterianas. Estruturalmente, ambas operam como um heterotetrâmero composto por duas proteínas GyrA e duas proteínas GyrB, para a girase, e duas proteínas ParC e duas ParE, na topo IV. Inúmeros agentes antibacterianos atuam inibindo a girase e a topo IV, tais como as quinolonas, cumarinas e algumas toxinas naturais, incluindo o CcdB. A toxina bacteriana CcdB, é uma pequena proteína de 11,7 kDa, contendo 101 resíduos de aminoácidos que, juntamente com o CcdA, faz parte de um sistema de morte celular programada do plasmídeo F, um fator de conjugação muito estudado em Escherichia coli. CcdB atua como uma toxina e o CcdA como a antitoxina. Na ausência de CcdA, CcdB pode matar a bactéria através de um mecanismo, ainda pouco conhecido, que envolve a girase e/ou a topo IV, assim como a região C-terminal da toxina CcdB (Trp-99 a Ile-101). Neste trabalho está descrita a obtenção de uma série de seqüências peptídicas miméticas, racionalmente projetadas, baseadas na estrutura primária do CcdB natural, com o objetivo de melhor entender o mecanismo de inibição da atividade de ambas, DNA girase e topo IV, pelo CcdB, e também propor um novo grupo de moléculas com potencial atividade antibacteriana.
Most bacteria posses two type IIA topisomerases, DNA gyrase and topoisomerase IV (topo IV), that together help manage DNA integrity and topology. Gyrase primarily introduces negative supercoils into DNA, and the topo IV, although closely related to gyrase, preferentially decatenates DNA and relaxes positive supercoils, essential functions for bacterial DNA replication and transcription. This makes of the gyrase and topo IV important targets for antibacterial drugs. Structurally both operate as a heterotetramer formed by two GyrA and two GyrB proteins for girase, and two ParC and two ParE proteins for topo IV. A large number of antibacterial agents act in the inhibition of the gyrase and topo IV, such as quinolones, coumarins, and some natural toxins including the protein CcdB. The bacterial toxin CcdB is a 11.7 kDa protein with 101 amino acids that with CcdA form a programmed cell death system of F plasmid, a conjugation factor widely studied in E. coli. CcdB acts like a toxin and CcdA as the antitoxin. In the CcdA absence, CcdB can kill the cell by an unclear mechanism that involves gyrase and/or topo IV, as well as the CcdB C-terminal region (Trp-99 to Ile-101). In this work it is described the obtaining of a several peptides mimics, rationally design, based on the primary structure of natural CcdB toxin, to a better understanding the inhibition mechanism of the activity of the gyrase and topo IV, by CcdB toxin, and also propose a new molecules group with potential antibacterial activity. The peptides mimics were synthesized by Solid Phase methodology (SPPS), purified and analyzed by liquid chromatography (HPLC) and identified by LC/ESI-MS and by amino acid analysis. The inhibition capacity of the peptide mimics was tested by electrophoresis agarose gels and by bacterial growth in liquid medium assays.
Most bacteria posses two type IIA topisomerases, DNA gyrase and topoisomerase IV (topo IV), that together help manage DNA integrity and topology. Gyrase primarily introduces negative supercoils into DNA, and the topo IV, although closely related to gyrase, preferentially decatenates DNA and relaxes positive supercoils, essential functions for bacterial DNA replication and transcription. This makes of the gyrase and topo IV important targets for antibacterial drugs. Structurally both operate as a heterotetramer formed by two GyrA and two GyrB proteins for girase, and two ParC and two ParE proteins for topo IV. A large number of antibacterial agents act in the inhibition of the gyrase and topo IV, such as quinolones, coumarins, and some natural toxins including the protein CcdB. The bacterial toxin CcdB is a 11.7 kDa protein with 101 amino acids that with CcdA form a programmed cell death system of F plasmid, a conjugation factor widely studied in E. coli. CcdB acts like a toxin and CcdA as the antitoxin. In the CcdA absence, CcdB can kill the cell by an unclear mechanism that involves gyrase and/or topo IV, as well as the CcdB C-terminal region (Trp-99 to Ile-101). In this work it is described the obtaining of a several peptides mimics, rationally design, based on the primary structure of natural CcdB toxin, to a better understanding the inhibition mechanism of the activity of the gyrase and topo IV, by CcdB toxin, and also propose a new molecules group with potential antibacterial activity. The peptides mimics were synthesized by Solid Phase methodology (SPPS), purified and analyzed by liquid chromatography (HPLC) and identified by LC/ESI-MS and by amino acid analysis. The inhibition capacity of the peptide mimics was tested by electrophoresis agarose gels and by bacterial growth in liquid medium assays.
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Palavras-chave
Bioquímica, Peptídeos, Proteínas
Como citar
GARRIDO, Saulo Santesso. Novos inibidores peptídicos de topoisomerases bacterianas estruturalmente derivados da proteína CcdB. 2007. 115 f. Tese (doutorado) - Universidade Estadual Paulista, Instituto de Química., 2007.