Role and Mechanism of Suppressed Apoplastic Serine Hydrolase Activities during Infection with Pseudomonas syringae
Plant Genetics and Genomics
Final Report Abstract
Most plant pathogens live in the apoplast (extracellular space), but how they manipulate this complement is poorly understood. Shot-gun proteomics revealed the accumulation of different proteins in the apoplast upon infection of wild tobacco plants with bacterial pathogens. Besides hydrolytic enzymes, also plant-derived Kunitz inhibitors accumulate in the apoplast during infection. Depletion of this protein enhances bacterial growth, demonstrating that this protein plays an important role in immunity. Using activity-based proteomics, we discovered that the activities of secreted serine proteases are suppressed by an inhibitor that accumulates in infected tissues. Plant-encoded Kunitz inhibitors can suppress these enzymes, but the enzymes remain suppressed upon depletion of the Kunitz inhibitors, suggesting that other inhibitors are involved. Depletion of the serine proteases results in the disappearance of signals in the activity profile but this depletion has no effect on bacterial growth. These data suggest that the both the suppression of serine proteases as well as their contribution to immunity is regulated by redundant mechanisms. Current projects funded by the ERC are aimed at elucidating these mechanisms at the University of Oxford.
Publications
- (2014) Broad range glycosidase activity profiling. Mol. Cell. Proteomics. 13, 2787-2800
Chandrasekar, B., Colby, T., Emon, A. E. K., Jiang, J., Hong, T. N., Villamor, J. G., Harzen, A., Overkleeft, H. S., and Van der Hoorn, R. A. L.
(See online at https://doi.org/10.1074/mcp.O114.041616) - (2014) DIGE-ABPP by click chemistry: pairwise comparison of serine hydrolase activities from the apoplast of infected plants. Meth. Mol. Biol. 1127, 183-194
Hong, T. N., and Van der Hoorn, R. A. L.
(See online at https://doi.org/10.1007/978-1-62703-986-4_15) - Inhibitor discovery by convolution ABPP. Activity-Based Proteomics pp 47-56. Part of book series: Methods in Molecular Biology, vol 1491. Humana Press, New York, NY, 2017
Chandrasekar, B., Hong, T. N., and Van der Hoorn, R. A. L.
(See online at https://doi.org/10.1007/978-1-4939-6439-0_4)
