Title page for ETD etd-04302010-134259


Type of Document Master's Thesis
Author Lucas, Andrew Thomas
URN etd-04302010-134259
Title Structural Basis for Dishevelled-2 Association to the Plasma Membrane
Degree Master of Science
Department Biology
Advisory Committee
Advisor Name Title
Finkielstein, Carla V. Committee Chair
Capelluto, Daniel G. S. Committee Co-Chair
Bevan, David R. Committee Member
Keywords
  • phosphatidic acid
  • DEP
  • Dishevelled-2
  • pH-dependent
Date of Defense 2010-04-16
Availability unrestricted
Abstract
The Wingless (Wnt) signaling pathway is one of the critical developmental pathways for control of cell differentiation, proliferation, and cell growth. The DEP domain, located on the Cterminus of Dishevelled (Dvl), plays a role in cytoplasm-membrane association, which branches the canonical and non-canonical Wnt signaling pathway within the cell. It has been suggested that the DEP domain requires the recruitment of ionic lipids, such as phosphatidic acid, to regulate its localization to the plasma membrane and association to the frizzle receptor. However, the physical mechanism for DEP association to the plasma membrane is still unknown. We show that mDvl2-DEP interacts with phosphatidic acid at a distinct patch on the surface formed by a positively charged surface area by NMR spectroscopy. The binding of this interaction was also found at physiologically relevant concentration using fluorescence spectroscopy. We also determined that the interaction is pH-dependent and regulated through a ‘histidine switch’ mechanism at His464 and His465 where there is increased association of mDvl2-DEP to the plasma membrane at higher pH values (7.5). This association is based on tertiary structure conformational changes with rearrangement of the loop regions by a change in local pH, not its interaction with phosphatidic acid. Overall, our work will contribute to elucidate how cells regulate their developmental pathways through localized molecular interactions.
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