Faculty Assistant

Anna Schmedel
Phone: 609-258-5028

Research Focus

Intracellular Trafficking

One major focus of the research in my group is to understand the protein machinery that generates the interior architecture of cells by guiding the movement and fusion of intracellular transport vesicles. All eukaryotic cells contain a profusion of membrane-bounded compartments. Traffic among these compartments is brisk. Cargo is transported in membrane vesicles that bud from one compartment, travel through the cell, and deliver their contents by fusing with another compartment. Underlying this intricate choreography is a set of proteins and protein complexes responsible for the creation, movement, docking, and fusion of vesicles. Our lab seeks to understand the design principles that endow these protein nanomachines with the ability to manipulate membrane vesicles, thereby powering a bustling intracellular transportation network.

Several of our current projects involve structural and mechanistic studies of large multi-subunit protein complexes that orchestrate the docking and fusion of transport vesicles. These complexes guide cargo-laden vesicles to their destinations and coordinate the activities of other components of the trafficking machinery, including the 'SNARE' proteins that catalyze membrane fusion itself. We are investigating the structure and function of these complexes using an array of technologies including x-ray crystallography, electron microscopy, site-directed mutagenesis, in vitro reconstitution, and a suite of spectroscopic techniques.

X-ray structure of Sar1, a GEF (GTP exchange factor) essential for transport vesicle formation, reveals a critical bound K+ ion that stabilizes the active site.

The initial recognition between a vesicle and its membrane target, on the other hand, is mediated by large protein complexes called tethering factors. Tethering factors act upstream of SNARE complex assembly and play key roles in determining the specificity of trafficking. Because little is known about the structures of tethering factors or the mechanism(s) by which they act, we have recently initiated biochemical and biophysical studies of these key protein complexes.


Quorum Sensing

A second major focus within our group is bacteria, and the remarkable finding that these single-celled organisms communicate with one another by emitting and receiving small-molecule signals. We are interested in cataloging the signal molecules and in understanding their biosynthesis and detection. Moreover, since bacteria often respond to these signals in undesirable ways – like forming antibiotic-resistant biofilms or mounting an attack on a human host – we are interested in discovering and characterizing molecules that interfere with bacterial communication. We are investigating these issues using a range of biochemical and biophysical approaches. For example, we are attempting to determine the crystal structures of the enzymes responsible for synthesizing the signal molecules, and of the receptors responsible for detecting them.

X-ray structures of CviR, a quorum sensing receptor, bound to either a signal molecule (cyan) or an antagonist (gray), reveals the basis for quorum sensing inhibition.

We have also begun to identify antagonists – molecules that inhibit signaling – and we are interested in using biochemical and structural methods to figure out how they work and how they might be improved by rational design. Finally, in collaboration with other Princeton labs in the molecular biology, chemistry, and physics departments, we are trying to understand how bacteria integrate the information they receive via multiple different signal molecules to craft an appropriate response.

Research Areas
Chemical Biology

Advisory Board, PLoS Biology (2012-present)

Clare Hall Life Member, Cambridge UK (2007-present)

Beckman Young Investigator (1995-1997)

Searle Scholar (1995-1998)

Selected Recent Publications

Baker, R. W.; Jeffrey, P. D.; Hughson, F. M., "Crystal Structures of the Sec1/Munc18 (SM) Protein Vps33, Alone and Bound to the Homotypic Fusion and Vacuolar Protein Sorting (HOPS) Subunit Vps16." Plos One 2013, 8 (6).

Bharucha, N.; Liu, Y.; Papanikou, E.; McMahon, C.; Esaki, M.; Jeffrey, P. D.; Hughson, F. M.; Glick, B. S., "Sec16 influences transitional ER sites by regulating rather than organizing COPII." Molecular Biology of the Cell 2013, 24 (21), 3406-3419.

McMahon, C.; Studer, S. M.; Clendinen, C.; Dann, G. P.; Jeffrey, P. D.; Hughson, F. M., "The Structure of Sec12 Implicates Potassium Ion Coordination in Sar1 Activation." Journal of Biological Chemistry 2012, 287 (52), 43599-43606.

Cavanaugh, L. F.; Chen, X.; Richardson, B. C.; Ungar, D.; Pelczer, I.; Rizo, J.; Hughson, F. M., "Structural analysis of conserved oligomeric golgi complex subunit 2." Journal of Biological Chemistry 2007, 282 (32), 23418-23426.

Chen, G.; Swem, L. R.; Swem, D. L.; Stauff, D. L.; O'Loughlin, C. T.; Jeffrey, P. D.; Bassler, B. L.; Hughson, F. M., "A Strategy for Antagonizing Quorum Sensing." Molecular Cell 2011, 42 (2), 199-209.

Yen, W.-L.; Shintani, T.; Nair, U.; Cao, Y.; Richardson, B. C.; Li, Z.; Hughson, F. M.; Baba, M.; Klionsky, D. J., "The conserved oligomeric Golgi complex is involved in double-membrane vesicle formation during autophagy." Journal of Cell Biology 2010, 188 (1), 101-114.

Hughson, F. M.; Reinisch, K. M., "Structure and mechanism in membrane trafficking." Current Opinion in Cell Biology 2010, 22 (4), 454-460.

Lees, J. A.; Yip, C. K.; Walz, T.; Hughson, F. M., "Molecular organization of the COG vesicle tethering complex." Nature Structural & Molecular Biology 2010, 17 (11), 1292-U139.

Ren, Q.; Wimmer, C.; Chicka, M. C.; Ye, S.; Ren, Y.; Hughson, F. M.; Whiteheart, S. W., "Munc13-4 is a limiting factor in the pathway required for platelet granule release and hemostasis." Blood 2010, 116 (6), 869-877.

Ren, Y.; Yip, C. K.; Tripathi, A.; Huie, D.; Jeffrey, P. D.; Walz, T.; Hughson, F. M., "A Structure-Based Mechanism for Vesicle Capture by the Multisubunit Tethering Complex Dsl1." Cell 2009, 139 (6), 1119-1129.

Richardson, B. C.; Smith, R. D.; Ungar, D.; Nakamura, A.; Jeffrey, P. D.; Lupashin, V. V.; Hughson, F. M., "Structural basis for a human glycosylation disorder caused by mutation of the COG4 gene." Proceedings of the National Academy of Sciences of the United States of America 2009, 106 (32), 13329-13334.

Kelly, R. C.; Bolitho, M. E.; Higgins, D. A.; Lu, W.; Ng, W.-L.; Jeffrey, P. D.; Rabinowitz, J. D.; Semmelhack, M. F.; Hughson, F. M.; Bassler, B. L., "The Vibrio cholerae quorum-sensing autoinducer CAI-1: analysis of the biosynthetic enzyme CqsA." Nature Chemical Biology 2009, 5 (12), 891-895.

Tripathi, A.; Ren, Y.; Jeffrey, P. D.; Hughson, F. M., "Structural characterization of Tip20p and Dsl1p, subunits of the Dsl1p vesicle tethering complex." Nature Structural & Molecular Biology 2009, 16 (2), 114-123.

Neiditch, M. B.; Federle, M. J.; Pompeani, A. J.; Kelly, R. C.; Swem, D. L.; Jeffrey, P. D.; Bassler, B. L.; Hughson, F. M., "Ligand-induced asymmetry in histidine sensor kinase complex regulates quorum sensing." Cell 2006, 126 (6), 1095-1108.

Togneri, J.; Cheng, Y.-S.; Munson, M.; Hughson, F. M.; Carr, C. M., "Specific SNARE complex binding mode of the Sec1/Munc-18 protein, Sec1p." Proceedings of the National Academy of Sciences of the United States of America 2006, 103 (47), 17730-17735.

Ungar, D.; Oka, T.; Vasile, E.; Krieger, M.; Hughson, F. M., "Subunit architecture of the conserved oligomeric golgi complex." Journal of Biological Chemistry 2005, 280 (38), 32729-32735.

Neiditch, M. B.; Federle, M. J.; Miller, S. T.; Bassler, B. L.; Hughson, F. M., "Regulation of LuxPQ receptor activity by the quorum-sensing signal autoinducer-2." Molecular Cell 2005, 18 (5), 507-518.

Oka, T.; Vasile, E.; Penman, M.; Novina, C. D.; Dykxhoorn, D. M.; Ungar, D.; Hughson, F. M.; Krieger, M., "Genetic analysis of the subunit organization and function of the conserved oligomeric golgi (COG) complex - Studies of Cog5- and Cog7-deficient mammalian cells." Journal of Biological Chemistry 2005, 280 (38), 32736-32745.

Miller, S. T.; Xavier, K. B.; Campagna, S. R.; Taga, M. E.; Semmelhack, M. F.; Bassler, B. L.; "Hughson, F. M., Salmonella typhimurium recognizes a chemically distinct form of the bacterial quorum-sensing signal Al-2." Molecular Cell 2004, 15 (5), 677-687.

Zweifel, M. E.; Leahy, D. J.; Hughson, F. M.; Barrick, D., "Structure and stability of the ankyrin domain of the Drosophila Notch receptor." Protein Science 2003, 12 (11), 2622-2632.

Munson, M.; Hughson, F. M., "Conformational regulation of SNARE assembly and disassembly in vivo." Journal of Biological Chemistry 2002, 277 (11), 9375-9381.

Chen, X.; Schauder, S.; Potier, N.; Van Dorsselaer, A.; Pelczer, I.; Bassler, B. L.; Hughson, F. M., "Structural identification of a bacterial quorum-sensing signal containing boron." Nature 2002, 415 (6871), 545-549.

Lerman, J. C.; Robblee, J.; Fairman, R.; Hughson, F. M., "Structural analysis of the neuronal SNARE protein syntaxin-1A." Biochemistry 2000, 39 (29), 8470-8479.

Waters, M. G.; Hughson, F. M., "Membrane tethering and fusion in the secretory and endocytic pathways." Traffic 2000, 1 (8), 588-597.

Munson, M.; Chen, X.; Cocina, A. E.; Schultz, S. M.; Hughson, F. M., "Interactions within the yeast t-SNARE Sso1p that control SNARE complex assembly." Nature Structural Biology 2000, 7 (10), 894-902.