Mechanism of Intrinsic Hydrolysis in Small GTPases

Northeastern University, Boston MA

Investigators

Abstract

Intellectual Merit The superfamily of small GTPases includes five distinct groups of proteins that collectively touch on virtually all aspects of cellular function. They are inactive when bound to guanosine diphosphate (GDP) and functionally active when bound to the triphosphate form (GTP). GTPases have been very well studied for over 25 years and a general mechanism through which they are regulated is so well accepted that it routinely appears in Biochemistry and Cell Biology texts books. This project is based on a paradigm-shifting hypothesis that modifies this mechanism for some GTPases under particular circumstances, elucidating a subtle level of regulation associated with different forms of the GTP-bound protein. The research performed under this project focuses on Ras GTPase as a model for elucidating the chemical mechanism through which its function is deactivated in the newly discovered context, tests the mechanism on a second GTPase and uses computational approaches to look at sequence patterns across the family, mining the database of GTPase structures to assess the generality of the regulatory mechanism recently uncovered with aid from previous NSF support. This project will use multidisciplinary approaches focused on X-ray crystallography, neutron crystallography, quantum mechanics/molecular mechanics calculations (QM/MM), kinetic experiments and a crystallographic water analysis across the superfamily of GTPases using our in-house program Detection of Related Solvent Positions (DRoP) developed with previous NSF funding. Broader Impact The project supports three graduate students who will be trained in a thriving and diverse research and educational environment where mentoring is an important aspect of teamwork in the group at all levels of the academic ladder. Each will work closely with and mentor an undergraduate student on the project. Undergraduates constitute and integral part of the research, engaged in the Co-op program that supports Northeastern undergraduates for extended period of full time in the laboratory. The PI is developing strong alliances with minority serving institutions through the Northeastern Faculty Seminar Program, which she has initiated since arriving at Northeastern. The goal is to increase the diversity of applicants to the Ph.D. program in Chemical Biology while engaging minority students in exciting research that will promote long-term commitment to science. Through a partnership with Quality Education for Minorities (QEM) network the PI is reaching out to undergraduates from minority-serving institutions that do not have research opportunities. Two minority undergraduate students will be supported for summer research during the duration of the project. Each will have a graduate student mentor on the project and will work closely with the PI to assure effective learning and productivity in the laboratory.