Class II bacteriocins of Streptococcus pyogenes

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The bacterium known as Streptococcus pyogenes can frequently cause a range of human infections, however the 'natural' habitat for this organism is a carriage, non-disease state in the throat or on the skin. This suggests that this bacterium is adept in avoiding recognition by the immune system, but must also be able to compete with other endogenous microorganisms within this limited biological niche. Our NSERC-funded research program had previously discovered that Streptococcus pyogenes can produce small molecules (called bacteriocins) that can kill other bacteria. The molecules were curiously not produced when the bacteria were grown under laboratory conditions, but they were 'turned on' when the bacteria was used in a mouse model of throat colonization. This application will discover the mechanisms that Streptococcus pyogenes uses to control the production of these bacteriocins and will uncover what happens when different bacteriocins are mixed together with the hypothesis that this will result in killing of a broader range of competitor bacteria. The application will also try to understand the mechanisms by how Streptococcus pyogenes is protected from killing by it's own bacteriocins, a concept known as bacteriocin immunity. This work should help to understand the evolution and ecology of Streptococcus pyogenes.