Improving understanding of triple-helical collagen structure, self-assembly, and supramolecular organization

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Collagen is the most abundant protein in animals ranging from sponges to humans. It is a major component of skin, bones, cartilage and tendons, where it forms fibres. Alternately, it forms a scaffold-like support layer called the basement membrane, crucial for formation and maintenance of other tissues. Its molecular structure and the way in which it assembles into tissue or basement membrane are not well understood.I use two techniques to study proteins. First, with an atomic force microscope, a tiny, sharp tip is scanned over a protein surface and moved up or down in response to its topography. This provides a clear picture of the features of the protein surface, and allows us to observe events such as collagen fibre formation. This microscope can also be used to measure the amount of force required to pull apart two interacting collagen proteins, which provides valuable information about the way the two proteins are held together and the strength of their interaction. Unfortunately, it is difficult to use this microscope to identify the exact atomic composition of the protein or the interacting atoms giving rise to the forces measured. With nuclear magnetic resonance spectroscopy, on the other hand, individual atoms within a protein can be identified and studied. This technique allows a picture of the three-dimensional arrangement of atoms within collagen to be built, assisting interpretation of the microscopic picture of the collagen surface. Regions involved in binding to a second collagen protein and causing measured interaction forces can also be identified. The information obtained by these two techniques is therefore highly complementary, but they are not routinely used together.My research program will use protein models of collagen shorter than the full-length natural collagen. These will be engineered and produced to be suitable for study by both of these biophysical methods. This will allow us to fill in major gaps in our knowledge of collagen and its function in animals, including humans.