LIz Vanderlinde

University of Regina, Biology, Graduate Student

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Papers by LIz Vanderlinde

Mutation of the sensor kinase chvG in Rhizobium leguminosarum negatively impacts cellular metabolism, outer membrane stability, and symbiosis.

Journal of Bacteriology, Jan 1, 2011

Two-component signal transduction systems (TCS) are a main strategy used by bacteria to sense and... more Two-component signal transduction systems (TCS) are a main strategy used by bacteria to sense and adapt to changes in their environment. In the legume symbiont Rhizobium leguminosarum biovar viciae VF39, mutation of chvG, a histidine kinase, caused a number of pleiotropic phenotypes. ChvG mutants are unable to grow on proline, glutamate, histidine, or arginine as the sole carbon source. The chvG mutant secreted smaller amounts of acidic and neutral surface polysaccharides and accumulated abnormally large amounts of poly-ß-hydroxybutyrate. Mutation of chvG caused symbiotic defects on peas, lentils, and vetch; nodules formed by the chvG mutant were small and white and contained only a few cells that had failed to differentiate into bacteroids. Mutation of chvG also destabilized the outer membrane of R. leguminosarum, resulting in increased sensitivity to membrane stressors. Constitutive expression of ropB, the outer membrane protein-encoding gene, restored membrane stability and rescued the sensitivity phenotypes described above. Similar phenotypes have been described for mutations in other ChvG-regulated genes encoding a conserved operon of unknown function and in the fabXL genes required for synthesis of the lipid A very-long-chain fatty acid, suggesting that ChvG is a key component of the envelope stress response in Rhizobium leguminosarum. Collectively, the results of this study demonstrate the important and unique role the ChvG/ChvI TCS plays in the physiology, metabolism, and symbiotic competency of R. leguminosarum.

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Atomic force microscopy of a ctpA mutant in Rhizobium leguminosarum reveals surface defects linking CtpA function to biofilm formation

…, Jan 1, 2011

Atomic force microscopy was used to investigate the surface ultrastructure, adhesive properties a... more Atomic force microscopy was used to investigate the surface ultrastructure, adhesive properties and biofilm formation of Rhizobium leguminosarum and a ctpA mutant strain. The surface ultrastructure of wild-type R. leguminosarum consists of tightly packed surface subunits, whereas the ctpA mutant has much larger subunits with loose lateral packing. The ctpA mutant strain is not capable of developing fully mature biofilms, consistent with its altered surface ultrastructure, greater roughness and stronger adhesion to hydrophilic surfaces. For both strains, surface roughness and adhesive forces increased as a function of calcium ion concentration, and for each, biofilms were thicker at higher calcium concentrations.

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