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8.3 Microbiology and Biodegradation: A New Bacterial Communication System

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Final rept. 1 Jul 2009-30 Jun 2013

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Many bacteria use homoserine lactone HSL quorum-sensing QS signals to communicate and to control gene expression in a cell-density dependent manner. Durinh this project we completed a first set of fundamental studies of a new p-coumaroyl-HSL pC-HSL microbial communication system. This system of communication was novel when it was discovered because it is not based on fatty acid metabolism. We were also interested in identifying other non-fatty acid acyl-HSL systems in other bacteria. pC-HSL is detected by a signal receptor and transcription factor named, RpaR. During the project period we 1 published a study characterizing RpaR, 2 discovered and published a description of an RpaR anti-sense RNA that inhibits rpaR translation. The cis-RNA represents a new layer of regulation that can be brought to bear on the activity of a QS system and 3 published a study describing a second aryl-HSL signal, cinnamoyl-HSL, produced by a photosynthetic Bradyrhizobium species. The cinnamoyl-HSL QS system operates at 1000-fold lower concentrations than do other QS systems. Certain features of this system allow Bradyrhizobium sp. to eavesdrop on other bacteria and to also avoid detection by other bacteria. These novel signals appear to control biofilm formation by the bacteria that produce them.

Subject Categories:

  • Medicine and Medical Research
  • Microbiology
  • Radio Communications

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