Proteomic analysis of streptococcus pyogenes

Zhang, Meng (2007) Proteomic analysis of streptococcus pyogenes. Doctoral thesis, Northumbria University.

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Abstract

Streptococcus pyogenes (group A streptococcus, GAS) is a major human Gram-positive pathogen that causes infections that normally occur in the respiratory tract, the skin, the wound, the lung, the bloodstream and/or muscle tissues and result in millions of deaths every year. To cause such infections, S. pyogenes produces a wide range of virulence factors. The destruction of connective tissue and the hyaluronic acid therein plays an important role in pathogenesis. S. pyogenes was propagated in hyaluronic acid rich growth media in an attempt to create a simple biological system that could reflect some elements of the pathogenesis. The growth of bacteria was analyzed in the hyaluronic acid rich media and control media and a proteomic approach was applied to identify those proteins that were differentially expressed by the streptococcal pathogens growing in the different media. The techniques of two dimensional gel electrophoresis and static nanospray mass spectrometry were optimized and proteome maps for S. pyogenes grown in both media were constructed. The differentially expressed proteins by S. pyogenes were identified and analyzed using bioinformatics. Our results showed that several recognized virulence factors of S. pyogenes were upregulated in hyaluronic acid rich media, including the Ml protein, a collagen-like surface protein and the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase, which has been shown to play important roles in streptococcal pathogenesis. Interestingly, two hypothetical proteins of unknown function were also up-regulated and detailed bioinformatics analysis showed that at least one of these hypothetical proteins is likely to be involved in GAS pathogenesis. It was therefore concluded that this simple biological system provided a valuable tool for the identification of potential streptococcal pathogens virulence factors.

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