Role of a Small GTPase in Coordinating Two Motility Systems

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A grant has been awarded to Dr. Hartzell at the University of Idaho to study proteins that are required for gliding movement of bacterial cells on surfaces. The model bacterium used for these studies, Myxococcus xanthus, uses two unrelated types of motors simultaneously to propel itself. One motor uses a fiber to pull the cell while the other motor releases a material that pushes the cell. Each motor system has a component for forward and reverse motion. Although recent studies have elucidated the two motor mechanisms, little is known about the process by which the two different motor systems are coordinated when the direction of movement switches. Dr. Hartzell and her students have identified proteins that appear to play a role in the motor switching pathway. They are using biochemical, genetic, and molecular approaches to investigate the mechanism by which the two motors are synchronized to generate thrust in the same direction and to reverse their orientation simultaneously. Initial work will focus on understanding the interactions between MglA, a small GTP-binding protein, and its partner, MasK, a tyrosine kinase protein. This project will support the scientific training of two graduate and several undergraduate students in biological systems. The lead investigator has actively encouraged young women and students of underrepresented groups to join her lab. The proteins that these students will study are related to proteins that are essential for growth and development of animal cells. Both Ras and MglA interact with other proteins, including tyrosine kinases, to regulate critical cellular processes. However, there are several fundamental differences between the highly conserved bacterial and human GTP-binding proteins and tyrosine kinases that only recently have been revealed. Hence these studies promise to provide important clues to the function and evolution of these essential proteins and the complex pathways they control.