Investigating a role for SUMOylation in the plant circadian clock

Post-translational modification of proteins plays a critical role in most cellular signalling processes. In eukaryotes, an important form of such modification is the attachment of a small polypeptide, Ubiquitin. In recent years one such class of Ub-related tag called small
ubiquitin-like modifiers (SUMO) has emerged as a very influential molecular regulator1. SUMO modification causes a wide range of affect on proteins from altering a protein's activity to changing a protein's sub-cellular location. In plants SUMOylation plays an important role with altered SUMOylation levels causing a broad range of phenotypes including altered stress responses.

The circadian clock is an internal device for measuring time, found in most organisms. It allows them to accurately predict and respond to temporal changes in the environment. The circadian clock regulates a huge range of biological processes. In plants, these include key agricultural traits such as flowering time, dormancy, water use efficiency, nitrogen metabolism and yield2.

Recent work has identified potential SUMOylation sites within key protein components of the circadian clock and has provided evidence that SUMOylation at these sites maybe altered in response to stress. This project aims to investigate the role of altered SUMOylation on the circadian clock mechanism under both ambient and stress inducing conditions. The clock will be assayed using whole plant and cellular level circadian assays. The project will then focus on specific sites of SUMOylation in key clock components, modify these sites and investigate function of these modified proteins in vivo. We will use computer simulation and experimental approaches to investigate the molecular and mechanistic effects of these specific SUMOylation events within the context of the circadian clock.


Training:
The proposed project will allow the successful PGR to develop skills in the following experimental areas:
Experimental design and statistical analysis:
You will learn methods in circadian analysis and experimental design. This will include measuring gene-expression with promoter luciferase constructs and analysis of circadian clock mutants. You will also learn how to assay the clock at the cellular level using microcopy approaches. You will have the opportunity to learn molecular biology technique.
Mathematical modeling of Biological systems
You will also learn how to represent biological processes using mathematical formalisms and most importantly, which formalisms are appropriate for a given biological process. You will go on to test your mathematical models comparing their behavior with that of the biological organism.
You will learn techniques in biochemistry, in particular protein modification based proteomics.

You will sit in on the appropriate university run courses, chosen for you depending on your current skill set.
You will have regular meetings with your supervisors who will guide you through; the relevant literature, project development, your technical development, scientific writing skills and oral presentations.