Lon-Mediated Regulation of Type III Protein Secretion in Pseudomonas Syringae

University Of Maryland, College Park, College Park MD

Investigators

Abstract

The pathogenicity and host range of Pseudomonas syringae, a plant pathogenic bacterium, has been linked to the activities of a type III protein secretion system (TTSS) that essentially injects bacterial proteins into cells of its host. These injected proteins alter the host cells to assist the growth of the bacterium in susceptible plants, but in resistant plants these proteins serve as a signal to initiate cellular defense mechanisms associated with disease resistance. The assembly of the TTSS in P. syringae is induced during the interaction with host cells and is coordinated by a complex genetic regulatory system. Positive- and negative-acting regulatory factors that control assembly of the TTSS have been identified. This project will elucidate how these regulatory factors transduce signals produced during the interaction with the host to regulate and coordinate assembly of the TTSS. This research will determine how the activity of a specific regulatory protease is controlled during the disease process, define the role of another regulatory protein, HrpV, in coordinating the assembly of the TTSS, examine a possible gating mechanism controlling when proteins are released from the bacteria, and elucidate how the activities of key transcriptional factors are modulated. The proposed experiments will provide new insight into molecular mechanisms for controlling bacterial disease and disease resistance in plants, but since several bacterial pathogens of mammals use a very similar mechanism, this research may have application to managing bacterial diseases of mammalian hosts.