Eukaryotic cells transport cargo between subcellular organelles, and to the plasma membrane for secretion, using small membrane-bound vesicles are carriers. The regulation of vesicular transport and membrane fusion processes are crucial for cellular morphology, growth, movement and secretion, including hormone release and neurotransmission. Many essential proteins are required for these processes, including the SNARE proteins and Sec1 that are involved in the membrane fusion process, the Rab and Rho GTPases, and an octameric tethering complex called the exocyst. Although the exocyst complex has been implicated in a number of different functions involved in recognition, tethering and quality control of SNARE assembly and fusion, none of these are well understood at the molecular level. We are using a multidisciplinary strategy of biochemical and biophysical techniques, combined with genetics and cell biological methods, in order to understand the molecular architecture and function of the exocyst complex. We study the exocyst proteins from the model organism Saccharomyces cerevisiae to take advantage of the wealth of genetic, cell biological and biochemical techniques available. Our studies aim to: 1) map the functional organization of the exocyst complex through biochemical studies in vitro and analyze mutants to test the function of the exocyst in vivo;(2) determine the 3D structure of the entire exocyst complex using electron microscopy, crystallography and molecular modeling;and (3) watch the exocyst tether vesicles at the single molecule level to analyze the requirements for tethering, and (4) dissect the role of the exocyst and Sec1 in SNARE complex assembly and membrane fusion. Because these proteins are conserved from yeast to human neurons, this research will advance our knowledge of how secretion and growth are regulated in all eukaryotic cells.

Public Health Relevance

Cellular growth, development, movement and communication absolutely require accurate vesicle targeting and membrane fusion;an essential component of these fundamental cell biological processes is the exocyst complex, which is conserved from yeast to man, and has been implicated in a variety of human diseases, such as cancer, diabetes, ciliopathies, and bacterial pathogenesis. Our studies of the exocyst and its regulation of membrane fusion proteins will lead to a molecular understanding of the function of the yeast exocyst complex. In addition, our research will also lead to the development of many technologies, constructs, reagents and ideas that will be valuable tools for studying how the exocyst complex regulates secretion in all eukaryotic cells.

Agency
National Institute of Health (NIH)
Type
Research Project (R01)
Project #
2R01GM068803-10
Application #
8764547
Study Section
Membrane Biology and Protein Processing Study Section (MBPP)
Program Officer
Ainsztein, Alexandra M
Project Start
Project End
Budget Start
Budget End
Support Year
10
Fiscal Year
2014
Total Cost
Indirect Cost
Name
University of Massachusetts Medical School Worcester
Department
Biochemistry
Type
Schools of Medicine
DUNS #
City
Worcester
State
MA
Country
United States
Zip Code
01655
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Morgera, Francesca; Sallah, Margaret R; Dubuke, Michelle L et al. (2012) Regulation of exocytosis by the exocyst subunit Sec6 and the SM protein Sec1. Mol Biol Cell 23:337-46
Jin, Yui; Sultana, Azmiri; Gandhi, Pallavi et al. (2011) Myosin V transports secretory vesicles via a Rab GTPase cascade and interaction with the exocyst complex. Dev Cell 21:1156-70
Redfern, Roberta E; Daou, Marie-Claire; Li, Li et al. (2010) A mutant form of PTEN linked to autism. Protein Sci 19:1948-56
MacDonald, Chris; Munson, Mary; Bryant, Nia J (2010) Autoinhibition of SNARE complex assembly by a conformational switch represents a conserved feature of syntaxins. Biochem Soc Trans 38:209-12
Furgason, Melonnie L M; MacDonald, Chris; Shanks, Scott G et al. (2009) The N-terminal peptide of the syntaxin Tlg2p modulates binding of its closed conformation to Vps45p. Proc Natl Acad Sci U S A 106:14303-8
Struthers, Marion S; Shanks, Scott G; MacDonald, Chris et al. (2009) Functional homology of mammalian syntaxin 16 and yeast Tlg2p reveals a conserved regulatory mechanism. J Cell Sci 122:2292-9
Croteau, Nicole J; Furgason, Melonnie L M; Devos, Damien et al. (2009) Conservation of helical bundle structure between the exocyst subunits. PLoS One 4:e4443
Songer, Jennifer A; Munson, Mary (2009) Sec6p anchors the assembled exocyst complex at sites of secretion. Mol Biol Cell 20:973-82
Munson, Mary (2009) Tip20p reaches out to Dsl1p to tether membranes. Nat Struct Mol Biol 16:100-2

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