Contribution of various multidrug resistance efflux transporters to the fitness and virulence of Pseudomonas syringae
T. HELMANN (1), S. Lindow (1) (1) University of California, Berkeley, U.S.A.

Plant pathogens such as Pseudomonas syringae encounter diverse plant-produced metabolites during colonization of both the apoplast and surfaces of plants. Successful epiphytic colonization or infection requires tolerance to such chemicals by either detoxification or active efflux from the cell. Pseudomonas syringae pv. syringae B728a harbors approximately 70 transporters, representing several protein families, that do not appear to be dedicated to the import or export of specific resources. Nine are members of the Resistance-Nodulation-Division (RND) transporter family that are likely to be relatively promiscuous in the substrates they remove. 38, 17, and 3 members of the Major Facilitator Superfamily (MFS), Drug/Metabolite Transporter (DMT) family, and Multi-Antimicrobial Extrusion protein (MATE) family, are present, and these families are likely to have more narrow substrate ranges. The expression of 27 of these transporters is significantly up-regulated during either epiphytic or apoplastic growth of P. syringae on bean, suggesting an important fitness contribution. Phylogenetic analysis reveals that while most efflux proteins are widely conserved in P. syringae strains, 9 are found in a limited subset of strains. While most of these efflux proteins remain to be characterized, mutational analysis indicates that several contribute to the fitness of P. syringae in and on plants.

Abstract Number: P3-70
Session Type: Poster