MORRIS BURKE, PHD
Professor of Biology
Professor of Physiology & Biophysics
Professor Burke's laboratory focuses on the structural basis of actomyosin-based motility in muscle and non-muscle cells at the level of the two interacting proteins myosin and actin. Myosin is a motor enzyme, so classified because it is able to support MgATP-dependent sliding movement of actin filaments. While this form of biological movement is coupled to the hydrolysis of MgATP, the structural basis for coupling the free energy of MgATP hydrolysis to produce mechanical work, when the two proteins interact, is not understood. In recent years a number of proteins with sequence homology to muscle myosin have been found in different tissues of vertebrates and invertebrates and these appear to be motor enzymes. Work in the laboratory is involved in characterizing: (i) the changes in the substructure of the myosin catalytic heavy chain subunit; (ii) the essential structural requirements enabling certain nucleotide and non-nucleotide analogs to support actomyosin motility. The laboratory is also involved in the expression and characterization of a number of non-conventional myosins such as nina C, which is found in the eyes of fruit flies, and a non-muscle form of myosin found in the embryos of fruit flies. The accompanying figure represents the results of probing the substructure of the myosin heavy chain by sequential denaturation as probed by limited proteolysis. The primary structure of the chain is represented inthe lower schematic as a line with the sequences of the two protease-labile "linker" segments within this chain shown.