Novel protein-protein interactions in ?Candidatus Liberibacter asiaticus?

FLAVIA LOTO; GONZALEZ, CLAUDIO F.; PADGETT, KAYLIE A.

Gainesville

Simposio; Microbiology and Cell Science Undergraduate Research Symposium; 2016

College of Liberal Arts and Science- University of Florida

newline">Huanglongbing disease (HLB) severely affects citrus trees and represents one of the greatest threats to the citrus industry. The disease is caused in part by a bacteria named ?Candidatus Liberibacter asiaticus? (CLas) which currently has no treatment toprevent or cure the disease, henceforth, different control strategies are being analyzed. The discovery of novel protein functions and the underlying protein-protein interactions are crucial for understanding the bacterium?s survival strategy within the host andcould be used as new targets for antimicrobial compounds. Global gene expression profiling done by Yan et al. (2013) revealed a protein, CLIBASIA_03135, experiencing a near 8-fold increase in planta versus expression in its insect vector. The aim of thisstudy was to identify possible binding partners of CLIBASIA_03135, a protein whose function remains elusive. The immunoprecipitation assays were conducted with cell lysates from Liberibacter crescens, Sinorhizobium meliloti, and Escherichia coli.CLIBASIA_03135 co-precipitated with proteins such as Hsp40, a co-chaperone from E. coli, as well as the ATP-dependent protease ATP binding subunit ClpX from S. meliloti. From L. crescens, the closest cultivatable species known, GroEL homologue wasidentified as a possible binding partner. In order to confirm this last interaction, two-hybrid assays following LacZ activity as a reporter were conducted. The -galactosidase activity increased two-fold in the strain containing the plasmids that carried bothCLIBASIA_03135 and GroEL homologue when compared to the control strains harboring both empty plasmids. The effect of the temperature in this system was also evaluated. It was found that the highest interaction occurred at 37°C. The proteins identifiedas potential binding partners in this study may be involved in the homeostasis and the stress response of the cell, suggesting a similar role for CLIBASIA_03135.