Greenberg Group

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 This week we profile a recent publication in PNAS from Dr. Peter Greenberg (left)
and Bruna Coutinho (second from right) at the University of Washington.

Can you provide a brief overview of your lab’s current research focus?

The research in the Greenberg laboratory focuses on the emerging field of sociomicrobiology – the group-behaviors of microbes. We are interested in the biochemistry and molecular biology of environmental sensing/response with a particular emphasis on a form of chemical communication between bacteria termed “quorum sensing”. In quorum sensing, bacteria synthesize chemical signals as cues to coordinate activities of individuals in groups. This signaling plays a critical role in the development of many bacterial infections.

 What is the significance of the findings in this publication?

In many plant-associated bacteria, the quorum sensing receptor no longer senses its own quorum sensing signals – instead the system has evolved to recognize compounds present in the plant host. Although these plant-responsive receptors were described more than a decade ago, the factor(s) they sense were unknown until now. Our work describes the identification of an ethanolamine-derived molecule that serves as signal for a plant-responsive receptor in a Poplar tree endophyte, Pseudomonas sp GM79. Ethanolamine is a building block for plant membrane phospholipids and signaling molecules. This discovery connects at least one of the plant-responsive receptors to a growing understanding of ethanolamine chemistry and responses of bacterial cells to ethanolamine and its derivatives. These plant-responsive systems regulate virulence and symbiosis in plant-associated bacteria, so defining how they work and the plant molecules that control them could contribute to improved crop disease management and the resourceful use of biofertilizers.

 What are the next steps for this research?

Our discovery leads to several questions regarding the biology and biochemistry of this interkingdom signaling system: do similar receptors in other plant-associated bacteria respond to the same, or related, ethanolamine-derived signal? What impact does the signal have on plant host-bacteria interactions? These are just some of the questions we are interested in answering in the near future.

If you’d like us to mention your funding sources, please list them.

This work is part of a collaborative, multidisciplinary project with the Plant-Microbe Interfaces (PMI) Scientific Focus Area at Oak Ridge National Laboratory, funded by the Office of Biological and Environmental Research (BER) within the US Department of Energy (DOE) Office of Science. More information on the PMI research can be found at:

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