Publicação
Biologia celular da síntese da cápsula de Streptococcus pneumoniae
| Resumo: | Streptococcus pneumoniae is a major human pathogen capable of causing a wide range of diseases in humans. CPS (capsular polysaccharide) is a major virulence factor in these pathogenic bacteria. Biosynthesis of CPS RU (repeated units) proceeds by the sequential, ordered transfer of activated sugar residues to a lipid carrier molecule by committed GTs (glycosyltransferases). WchA is the first of this GT family of proteins to act, and is responsible for the addition of the first sugar to the lipid carrier molecule. Following RU addition, the CPS is transported across the cell membrane and is then attached to the cell wall. Wzh, Wzd and Wze are all thought to be regulators of this process and are believed to act as a complex within the membrane, however the exact function and localization is unknown. S. pneumoniae is a microaerofilic microorganism. This type of metabolism is not compatible with the usage of Green Fluorescent Protein (GFP) for cellular biology studies. In this thesis we report the construction of a plasmid that allows the expression of an alternative fluorescent protein, mCherry, without any signs of toxicity. With this new tool we were able to express fluorescent derivates of capsular biosynthesis proteins in S. pneumoniae. We were particularly interested in the Wze-mCherry fusion as Wze is thought to play a major role in this process and it has been proposed that Wze could be the CPS polymerase. Taking into account the results that were obtained here, we were able to fit the process of capsular synthesis into the existing model for cell division. We propose that, in contrast to peptidoglycan synthesis which is proposed to occur at both the septum and at the periphery, capsular synthesis occurs in only one place: the septum |
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| Autores principais: | Ferreira, Luís Filipe Encarnação Antunes |
| Assunto: | Biologia celular Streptococcus pneuminiae Teses de Mestrado |
| Ano: | 2010 |
| País: | Portugal |
| Tipo de documento: | dissertação de mestrado |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade de Lisboa |
| Idioma: | português |
| Origem: | Repositório da Universidade de Lisboa |
| Resumo: | Streptococcus pneumoniae is a major human pathogen capable of causing a wide range of diseases in humans. CPS (capsular polysaccharide) is a major virulence factor in these pathogenic bacteria. Biosynthesis of CPS RU (repeated units) proceeds by the sequential, ordered transfer of activated sugar residues to a lipid carrier molecule by committed GTs (glycosyltransferases). WchA is the first of this GT family of proteins to act, and is responsible for the addition of the first sugar to the lipid carrier molecule. Following RU addition, the CPS is transported across the cell membrane and is then attached to the cell wall. Wzh, Wzd and Wze are all thought to be regulators of this process and are believed to act as a complex within the membrane, however the exact function and localization is unknown. S. pneumoniae is a microaerofilic microorganism. This type of metabolism is not compatible with the usage of Green Fluorescent Protein (GFP) for cellular biology studies. In this thesis we report the construction of a plasmid that allows the expression of an alternative fluorescent protein, mCherry, without any signs of toxicity. With this new tool we were able to express fluorescent derivates of capsular biosynthesis proteins in S. pneumoniae. We were particularly interested in the Wze-mCherry fusion as Wze is thought to play a major role in this process and it has been proposed that Wze could be the CPS polymerase. Taking into account the results that were obtained here, we were able to fit the process of capsular synthesis into the existing model for cell division. We propose that, in contrast to peptidoglycan synthesis which is proposed to occur at both the septum and at the periphery, capsular synthesis occurs in only one place: the septum |
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