Academic Background

Mary Munson was a double major in Chemistry and Biology at Washington University(St. Louis), receiving her bachelor's degree in 1989. In 1996, she received her Ph.D.from Yale University in Molecular Biophysics and Biochemistry. She was a postdoctoral fellow in the Department of Molecular Biology at Princeton University, where she was awarded both American Heart Association and NIH postdoctoral fellowships. She joined the faculty of Biochemistry and Molecular Pharmacology in 2001.

Regulation of vesicle targeting and fusion

Our Research

Our investigations mainly focus on the Exocyst complex (Fig. 1), a protein complex essential for vesicle trafficking (exocytosis) in all eukaryotes. The proteins that form the Exocyst complex localize to secretory vesicles and to sites of active secretion at bud tips and mother-bud necks. These proteins are essential for cell viability, show physical and genetic interactions with the the membrane fusion proteins (SNAREs) and with each other, and their temperature-sensitive mutants have secretory blocks and accumulate secretory vesicles.

Our research has several aims: 1) biophysical and structural studies of the Exocyst proteins and their interactions with each other; 2) creation and testing of mutants in vivo, in order to elucidate the functions of the Exocyst proteins; 3) characterization of interactions between the Exocyst and other proteins required for exocytosis, such as the SNARE proteins, and regulators such as Sec1p and the small Rab GTPase Sec4p; and 4) genetic and proteomic identification of novel regulators of exocytosis and SNARE complex assembly. Additionally, we are characterizing the regulation of endocytosis by the Sec1-homolog Vps45p, through its interactions with the endosomal SNARE proteins.

Figure 1.Current model for the architecture of the exocyst complex

Potential Rotation Projects

Research in the Munson lab is focused on biochemical/biophysical and cell biological characterization of proteins in the exocyst complex. Potential rotation projects include the following:

• Cloning of various exocyst protein domains and point mutations. These will be expressed in E. coli for biochemical/structural studies, and their functions tested in yeast.
  
• Protein expression and purification. Develop purification strategies for several exocyst proteins and their domains, using chromatography methods such as ion exchange and gel filtration (Fig. 2).
  
• Characterization of the purified exocyst proteins. Protein structure, stability, oligomerization state and protein:protein interactions will be monitored by such techniques as circular dichroism, analytical ultracentrifugation and gel filtration (Fig. 3).
  
• Crystallography. We have determined the structure of the C-terminal domain of Sec6p (Fig. 4). Crystallization trials ofotherexocyst proteins and their domains are in progress.
  
• Design and test functional exocyst mutants in yeast. Mutants will be characterized using a variety of biochemical, cell biological, and microscopic techniques.
  
• Identify novel regulators of yeast exocytosis using a genetic screen. Mutants created in these screens are currently being tested and identified (Fig. 5). Their role in exocytosis will be explored