NMR investigations of blood coagulation: Conformational changes of membrane bilayers and proteins in blood coagulation.

摘要

A multitude of biological processes involve membranes and their associated membrane proteins. The interactions of these biological molecules lead to perturbations in their structure and dynamics. Understanding the variations in the constitution of these molecules as the result of functional interactions will provide insights into various biological processes. In this work, we employ solution and solid-state NMR to observe changes in dynamics and conformation of both membranes and membrane associated proteins upon interaction with other biological molecules. Initial studies focus on the interaction of neurological proteins alpha-synuclein and endosulfinealpha. Using chemical shift perturbation mapping we detail interactions of membrane bound alpha-synuclein with cAMP-regulated phosphoproteins, ARPP-19 and endosulfine-alpha. Additionally, we report that endosulfine-alpha is an intrinsically unstructured protein that undergoes a conformational change upon binding to membranes and detail the effects of phosphorylation on these structures. Furthermore, using a combination of solution and solid-state NMR, we investigate important interactions involved in blood coagulation. Structural and dynamics data of Ca2+-induced clusters of phosphatidylserine in membranes, important in blood clotting, is investigated using isotopically 13C, 15N-labeled phosphatidylserine in lipid bilayers. Finally, backbone resonances of the soluble, extracellular domain of tissue factor (absent the membrane binding transmembrane helix) are assigned in solution and nanocrystalline samples by solution and solid-state NMR respectively. The chemical shifts are then used to investigate changes in the extracellular domain of tissue factor when bound to the membrane by its native transmembrane helix.