Rhizobial attractants and their corresponding chemoreceptors

 

The spectrum of chemoattractants and ligand sensing in Rhizobia

Using the alfalfa-Sinorhizobium meliloti interaction as a model system, we aim to elucidate the molecular mechanisms that govern legume-rhizobia communications.  In S. meliloti, a varying soil milieu, metabolic diversity, and specific adaptations to host signals have led to the evolution of complex chemosensory system.  Eight chemoreceptors play a pivotal role in directing the bacterium toward nutrients sources and its plant host. We uncovered the central role of the chemoreceptor McpU in host-plant sensing. McpU is a direct sensor of most amino acids, all of which are exuded in millimolar concentrations by germinating alfalfa seeds. Recently, we discovered that S. meliloti McpX constitutes the first known bacterial betaine chemoreceptor. Betaines protect plants against environmental stress, but their role in communication with bacteria is a new discovery. The overarching goal of this project is to characterize the specific adaptations of S. meliloti chemoreception to the range of host-derived attractants.

References:

 

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