Artificial thylakoids: a bio-inspired platform for investigating assembly and organization in multi-layer membranes

All biological cells, from simple bacteria to human ones, are surrounded by 'membranes' comprised of lipids. Proteins within these membranes facilitate communication between the cell and its exterior, providing functions essential for the life of the cell. Some specialized biological membranes in cells' interior are stacked into multi-layers, allowing a high density of membrane proteins to be packed into a small volume. In plants, stacked membranes enhance the efficiency of photosynthesis, the process used to harness solar energy for growth. This proposal seeks to generate new 3-D arrangements of artificial membranes in the laboratory, to create new structures and functions not found in Nature.

A new "synthetic biology" approach will take the individual protein and lipid components from cells and recombine them into model stacked membranes on solid surfaces. Proteins normally involved in photosynthesis will be used to create well-defined artificial plant-like membranes which can then be used to explore natural processes in a controlled environment. They aim to (1) generate array-patterns of these stacked membranes rich in photosynthetic plant proteins, and (2) to investigate how assembly and protein organisation occurs in these model membranes to inform us on natural systems. Furthermore, these controlled, stacked membrane patterns are expected to have applications in modern nano-devices, such as biosensors.

The research will be led by Peter Adams, a scientist in the Molecular and Nanoscale Physics (MNP) group headed by Prof. Stephen Evans, at the University of Leeds, all experienced with artificial membranes. Collaborators at the University of Sheffield, Dr. Matt Johnson and Prof. C. Neil Hunter, are specialists in photosynthesis and will provide the purified plant proteins needed to assemble these membranes. They will use state-of-the-art "atomic force microscopy" to visualize the arrangement of membrane proteins at the nano-scale and determine their spatial organization. This technique uses a sharp probe to "see by touch" and can resolve minute features as small as one-millionth of a millimeter. Light-based "fluorescence microscopy" and "spectroscopy" techniques will be used to detect the optical properties of the photosynthesis proteins.

In conclusion, these efforts are expected to make substantial advances in the controlled design of 3-D, complex, functional biomaterials.

Biological cell membranes rely upon complex, hierarchical organization to elicit functional responses. To achieve specialized function some membranes form multilamellar stacked arrangements, such as the photosynthetic thylakoids of chloroplasts. This project aims to develop new artificial 3-D-organized stacked membranes inspired by chloroplast thylakoids. These controlled model membranes will act as a platform to test the factors influencing self-assembly, organisation and function in biological membranes, over multiple scales. A multi-disciplinary approach will combine surface chemistry, nano/micro fabrication, protein biochemistry, spectroscopy and various microscopies to fully explore these membranes.

I will use supported lipid bilayers (SLBs) as a template for building complex stacked membranes. New techniques for patterning membranes in 3-D will be developed. Firstly, I will produce lipid-only SLBs in controlled 2-D patterns and stacking from 2-100 bilayers. Subsequently, SLBs including plant membrane proteins will be generated, including Photosystem II (PSII) and Light Harvesting Complex II (LHC-II). These artificial membrane systems will be used to test the parameters driving membrane assembly in vitro, to inform on the natural system, including interlayer protein domain alignment, PSII array formation, phase segregation of proteins and energy-transfer properties. Atomic force microscopy and fluorescence microscopy (with spectral/ lifetime imaging) will reveal the protein organisation and confirm maintenance of light-harvesting function.

Success in these efforts will represent a major advance in the controlled design of 3-D complex, functional biomaterials. Other membrane proteins, e.g. signalling receptors, could be incorporated, allowing investigation of varied biological processes. Future applications could include artificial photosynthetic devices with enhanced absorption and biosensors with high-protein-density with improved recognition capability.

David Willetts, the UK government minister for Universities and Science, recently said: "Synthetic biology is one of eight key technology areas... playing an increasingly important part in the global economy over the coming years" (Mar 7, 2013). My proposed research is expected to develop new techniques for synthetic biology; nano/biotech companies could benefit with tools for developing new protein/membrane biohybrid devices. Specifically, our findings could constitute Intellectual Property (IP) of financial interest to UK companies. Further R&D will certainly be needed to exploit any newly developed techniques, leading to benefits over the next 5-10 years. More generally, my research would enhance the economic competitiveness of the UK by promoting the country as a world-leading centre for this emerging field and fostering national and international collaborations that enhance the British 'bio-economy'.

Local schools and museums could also benefit from my research, from the STEM outreach activities that I would carry out. I intend to deliver workshops and presentations in local schools other public forums such as science festivals about: (1) the wonder of plants and solar energy, and (2) nanotech and synthetic biology benefits in a future society. To an audience of adults, the benefits would be (i) cultural, knowledge about modern-day nanoscale science and (ii) effectively information about how scientific research provides worthwhile innovations and economic benefits to taxpayers. To an audience of school children, benefits would be (i) fun and enjoyment of science, (ii) inspiring the scientists of the future. These presentations would be delivered in years 2 and 3 of the fellowship, providing almost instant benefit from these communications.

Public policy makers may be interested in my research as a new form of synthetic biology and as a good use of solar energy research (plant models). As recommended in the RCUK's report "A Synthetic Biology Roadmap for the UK", socially responsible research with public dialogue is needed. Traditional synthetic biology has stirred up negative publicity due to public misunderstanding over genetic modification. My research would promote synthetic biology without the use of animal testing or genetic engineering of plants and could promote effective policy in this field. I will ensure that my findings are available to policy-makers, e.g. press releases by University of Leeds. Public policy can be on a timescale of many years, and may be judged by favourable regulations, funding and reports and changing public opinion.