Hello and welcome to my ePortfolio. Here you can find information relating to my Ph.D. research project as well as links to my publications and related links.
I am a third year Ph.D. student enrolled as part of the Midlands Integrative Bioscience Training Partnership (MIBTP) based at the University of Warwick. As a biochemist my primary interests are in understanding the structural and mechanistic aspects of biological systems. Using a variety of biochemical and biophysical techniques I hope to gain an insight into how biological molecules, particularly proteins, interact and how this relates to their functions in an organism.
I study proteins involved in a process called Clathrin Mediated Endocytosis (CME), which is essential to the function of higher multicellular organisms. This process is integral to a wide variety of process including: synaptic function, cell polarity, cell signalling, development, membrane protein recycling, and nutrient uptake. Because of this CME is also implicated in a wide variety of disease states including cancer and Huntington’s. In addition this system is often hijacked by viruses and bacterial toxins in order to gain access to the cell. Therefore understanding this process will give us insights into how best to combat these diseases.
What is Clathrin Mediated Endocytosis?
CME occurs at the plasma membrane of cells where cargo that needs to enter the cells is detected. The process begins through the recruitment of clathrin and various adaptor proteins that mediate interactions between clathrin, the plasma membrane, the cargo and each other. This coat like mesh induces membrane curvature and in conjunction with the cell cytoskeleton draws the cargo in. Next, dynamin constricts the neck of the invagination thereby forming a vesicle inside the cell. The final step is to recycle the proteins that have made the coat, which occurs through the recruitment of Hsc70 and auxilin which actively remove the clathrin/adaptor coat.
Understanding Adaptor Proteins
Many adaptor proteins have been shown to promote clathrin assembly both in vitro and in vivo and can do so by binding to different parts of the clathrin structure. However the precise mechanism by which the proteins promote clathrin cage formation is not known. In addition many of the adaptor proteins are also present during the disassembly process and it is not know whether these proteins are actively removed from the complex or simply detach of their own accord.
In light of these facts my project has been to investigate if the promotion of assembly by these different binding mechanisms alters the structures the clathrin cage can adopt and if the mechanisms of promoting cage formation result in changes to cage disassembly. This will lead to a greater insight into the precise role of particular adaptor proteins, why different binding mechanisms are employed and further understanding as to the precise mechanism of clathrin cage disassembly.
Approaches and Current Insights
In order to study this process we purify proteins involved from multiple sources and re-constitute the system in vivo. By expressing recombinant functional and single cysteine mutants of Hsc70 and auxilin401-910, along with various adaptors proteins, we have been able to monitor the effect of the presence of adaptors on the structure and disassembly kinetics of clathrin cages. Using dynamic light scattering and electron microscopy we have been able to observe how adaptors such as epsin1 and Hip1/1R differentially alter the size distribution and structure of clathrin cages. And using techniques such as perpendicular light scattering and fluorescence we have been able to see how these adaptors alter the disassembly kinetics of clathrin cages by Hsc70 and auxilin and how mutations to auxilin alter the kinetics of disassembly.
Nicola J. Sinden, Michael J. Baker, David J. Smith, Jan-Ulrich Kreft, Timothy R. Dafforn, Robert A. Stockley, α-1-Antitrypsin variants and the proteinase/antiproteinase imbalance in chronic obstructive pulmonary disease. AJP - Lung Cellular and Molecular Physiology, Vol. 308 no. 2, L179-L190 DOI: 10.1152/ajplung.00179.2014
Awards and Positions
- Current Co-Chair of the School of Life Sciences Post-Graduate Staff and Student Liason Committee (SSLC)
- Winner of the FEBS Journal Poster Prize at EBSA European Biophysics Congress, Dresden, Germany, 2015
- Winner for Best Presentation (2nd place) at the Annual MIBTP Student Symposium, Leicester Unviersity, 2014
- Attended the EMBO course: The application of transient kinetic methods to biological macromolecules, 2015
Links to Colleagues
Co Supervisor: Professor Tim Dafforn
M dot Baker dot 2 at warwick dot ac dot uk