MID1 is a microtubule-associated ubiquitin (Ub) E3 ligase that targets the catalytic subunit of protein phosphatase 2A (PP2Ac) for degradation. PP2Ac regulates cellular pathways associated with metabolism, cell cycle, differentiation and apoptosis. MID1 facilitates the ubiquitination of PP2Ac, which marks the protein for degradation, by first binding alpha4, a regulatory subunit of PP2Ac, that then recruits PP2Ac. MID1 and alpha4 also play a key role in T and B lymphocyte maturation in mammals by down regulating PP2Ac within the target of rapamycin (mTOR) signaling pathway, which regulates cell growth and proliferation. MID1 contains three consecutive Ub E3 ligase domains, each possessing various degrees of in vitro E3 ligase activity, while the domains in tandem have significantly enhanced E3 ligase activity. These domains can interact with multiple Ub E2 conjugating enzymes and also appear to target alpha4 for Ub modification. The project will use NMR spectroscopy, biochemistry, and enzymology to identify mechanistically how MID1 is able to interact with multiple E2 enzymes and address how these interactions result in alpha4 and PP2A ubiquitination.
Broader Impacts The project will foster an attractive learning environment to encourage and recruit students, particularly undergraduate and high school students, to participate in basic science research. The PI has previously recruited over thirty undergraduate students to work on various aspects of research related to MID1 and alpha4. This research will allow for continued attraction of undergraduate and high school students and will foster a unique training experience in basic science research that cannot be obtained from the classroom. Four female undergraduate students have already been recruited from George Washington University, and the PI has used this research to educate and recruit high school students from Wheaton High School in Silver Spring, MD and Schools Without Walls in Washington, DC. The PI has discussed the impact of macromolecules on society and medicine with students from classes within the Biosciences Academy at Wheaton HS and will continue doing this every semester to promote science education to future generations. A greater outreach to high school students in the DC area is underway.
