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School of MedicineUniversity of Washington • Box 357735 • 1705 NE Pacific St • Seattle WA 98195
  Harwood Lab: Communication Using Novel HSLs    

Quorum sensing is a term used to describe cell-to-cell communication that allows cell density-dependent gene expression. 

We are interested in the cellular communication in members of the root microbiome of the fast-growing Eastern cottonwood tree, Populus deltoides (Poplar). Working in collaboration with E. Peter Greenberg and scientists at Oak Ridge National Laboratory, we found that quorum sensing signal synthase (luxI-homologs) and receptor (luxR-homologs) genes are prevalent in the genomes of Proteobacteria isolated from Poplar roots. Interestingly, many of these endophyte isolates encode an orphan LuxR-homolog that is unusual among LuxR-homologs because it does not respond to the bacterially-produced acyl-homoserine lactone quorum sensing signals – instead, it detects an unknown plant compound. We are currently working to identify this new quorum sensing signal.


Cluster of Rhodopseudomonas palustris cells overlaid with the structure of p-coumaroyl-homoserine lactone