Johnson, Sarah A.
Sarah is a first year trainee and is in the Molecular Biology IDP. Her research mentor is Dr. Arnold Berk. She received a B.S. degree in 2007 from Randolph College.
Mentor: Dr. Arnold Berk
In transcriptional regulation, the approximately 30-subunit metazoan Mediator (MED) complex forms a molecular bridge between activators and RNA polymerase II (Pol II) required to activate transcription, as well as promote the Pol II pre-initiation complex assembly. However, the massive size and complexity of MED hinders a clearer understanding of the specifics in the interactions between Pol II and MED subunits, and how they function in transcriptional regulation. Using a specialized CHO cell line, the A03.1 cell line, and confocal microscopy, I study the molecular interactions of individual MED subunits, of MED with activators, and of MED with Pol II by fusing them to fluorophores. Specifically, I analyze the MED7 and MED21 subunits in the middle module of MED, and its interactions with Pol II. The massive size and complexity of MED hinders a clearer understanding of the specifics of these potential changes and how they function in transcriptional regulation is poorly understood. In elucidating the specific molecular interactions that take place, I aim to contribute to a more precise understanding of how MED coordinates its many complex regulatory signals to influence transcription in higher eukaryotic organisms.
