The rapid and structured disassembly of plant proteomes during germination, senescence and defence are massive proteolytic events that underpin plant development and immunity. Surprisingly, however, the proteases responsible for these proteolytic events are yet unidentified. Because of their strong upregulation during proteolysis, papain-like cysteine proteases (PLCPs) are strong candidates. Indeed, chemical knock-out experiments indicate crucial roles for PLCPs in proteolysis. However, single and double mutants lacking PLCPs do not display proteolytic phenotypes, suggesting that they act redundantly (Lu et al., 2015; Pruzinska et al., 2016). The Arabidopsis genome encodes for 31 PLCPs that fall into nine different subfamilies (Richau et al., 2012). Members of several subfamilies are transcriptionally co-regulated, which predicts a cooperation or redundancy between PLCPs of different subfamilies.
The AIM OF THIS PROJECT is project is to unravel functions of the PLCP super family in the degradation of seed storage proteins, leaf senescence and hypersensitive cell death. The approach is to deplete multiple genes encoding PLCPs using genome editing combined with classical genetics and investigate the effect of PLCP depletion on protein degradation. We will investigate proteomes of mutant plants using PROTOMAP and TAILS to identify putative substrates and unravel redundant proteolytic cascades. We will compare this with substrate specificities of each PLCP determined by PICS (Huesgen & Overall, 2012). These techniques will be combined with protease activity profiling (Morimoto & Van der Hoorn, 2015) to monitor the effects of gene inactivation on the PLCP activity landscape. These activities will be combined with germination, senescence and disease assays to elucidate biological roles of the PLCPs.
This is an exciting, challenging project for a devoted, inquisitive minded student with an appetite for protein biochemistry and genetics. Experience with molecular cloning is essential, and practice working with Arabidopsis and/or proteins is advantageous. The student will be part of a strong, dynamic interdisciplinary research team that exploits similar approaches to study proteolysis in other plants.
There are three application deadlines, but you are strongly encouraged to apply in November or January.
- Friday 16 November 2018
- Friday 25 January 2019
- Friday 1 March 2019
* Note: Applications must be submitted by 12 noon (midday) on these days.
Please ensure that you contact potential supervisors well in advance of these deadlines. Later applications may be considered if places are available.
Prospective students are encouraged to apply to the Oxford Interdisciplinary Bioscience DTP. International applicants are encouraged to explore scholarship options that are available to them through the University of Oxford, their home countries or organisations such as the Commonwealth Scholarship Commission.
Pruzinska, A., Shindo, T., Niessen, S., Kaschani, F., Toth, R., Millar, A. H., and Van der Hoorn, R. A. L. (2017) Major Cys protease activities are not essential for senescence in individually darkened Arabidopsis leaves. BMC Plant Biol. 17, 4.
Morimoto, K., and Van der Hoorn, R. A. L. (2016) The increasing impact of activity-based protein profiling in plant science. Plant Cell Physiol. 57, 446-461.
Lu, H., Chandrasekar, B., Oeljeklaus, J., Misas-Villamil, J. C., Wang, Z., Shindo, T., Bogyo, M., Kaiser, M., and Van der Hoorn, R. A. L. (2015) Subfamily-specific probes for Cys proteases display dynamic protease activities during seed germination. Plant Physiol. 168, 1462-1475.
Richau, K., Kaschani, F., Verdoes, M., Pansuriya, T. C., Niessen, S., Stüber, K., Overkleeft, H. S., Bogyo, M., and Van der Hoorn, R. A. L. (2012) Subclassification and biochemical analysis of plant papain-like cysteine proteases displays subfamily-specific characteristics. Plant Physiol. 158, 1583-1599.
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