• Intracellular transport of proteins and lipids

The goal of my research is to identify the regulatory proteins that control vesicle transport in the yeast Saccharomyces cerevisiae, in order to understand how underlying defects in protein and lipid trafficking contribute to human disease. Vesicle transport is required to switch off signaling receptors that would otherwise promote unregulated cell growth. Retrograde transport also carries signals that promote the continued survival of neurons, and defects in the machinery responsible for retrograde transport are believed to be a cause of motor neuron disease. Because vesicle transport processes are highly conserved, they can be studied in a very simple organism, and the findings applied directly to the study of human cells. Yeast genetics is therefore a powerful tool for the discovery of fundamental cellular mechanisms relevant to human health.

Vesicle traffic is regulated by factors that select cargo for incorporation into a forming vesicle and direct its docking and fusion with the appropriate target membrane. The machinery that controls transport between two intracellular compartments - the endosome and the trans-Golgi network - is of particular interest because these compartments act as relay stations, directing a large number of different sorting events. We have used a genetic approach in the yeast model system to identify four components of a conserved protein complex (GARP: Golgi-associated retrograde protein complex) that directs the targeting of transport vesicles with the trans-Golgi network. We are currently using genetic, cell biological and biochemical techniques to analyze the interactions that link this vesicle targeting complex to other components of the membrane fusion machinery.

Recent advances in genome-wide phenotypic screening in yeast, combined with powerful bioinformatics analyses, hold great promise for the rapid and comprehensive identification of novel multi-subunit complexes. Functional genomics is expected to uncover most of the genes required for the trafficking of proteins and lipids through Golgi and endosomal compartments. In genome-wide screens, we have identified sets of genes likely to act together at common regulatory steps in protein sorting. We are now using biochemical/cell biological assays to characterize interacting proteins and analyze their role in protein and lipid trafficking in detail. Tackling a problem at many different levels - from genome-wide discovery studies in yeast, to the biochemical and cell biological characterization of specific protein complexes, to the investigation of homologous proteins in mammalian cells - allows an in-depth analysis of protein function and ensures that discoveries made in a simple model organism are efficiently translated to the study of medically relevant processes in mammalian cells.

Burston HE, Maldonado-Báez L, Davey M, Montpetit B, Schluter C, Wendland B, and Conibear E. Regulators of Yeast Endocytosis Identified by Systematic Quantitative Analysis Journal of Cell Biology (2009) PMID 0

Montpetit B, Conibear E. Identification of the novel TRAPP associated protein Tca17. Traffic (2009) PMID 19220810

Brumm J, Conibear E, Wasserman WW, Bryan J.: Discovery and expansion of gene modules by seeking isolated groups in a random graph process. PLoS ONE.2008;3(10):e3358.

Weissman Z, Shemer R, Conibear E, Kornitzer D.: An endocytic mechanism for haemoglobin-iron acquisition in Candida albicans. Mol Microbiol. 2008 Jul;69(1):201-17.

Meisler MH, Russ C, Montgomery KT, Greenway M, Ennis S, Hardiman O, Figlewicz DA, Quenneville NR, Conibear E, Brown RH Jr.: Evaluation of the Golgi trafficking protein VPS54 (wobbler) as a candidate for ALS. Amyotroph Lateral Scler. 2008 Jun;9(3):141-8.

Schluter C, Lam KK, Brumm J, Wu BW, Saunders M, Stevens TH, Bryan J, Conibear E.: Global analysis of yeast endosomal transport identifies the vps55/68 sorting complex. Mol Biol Cell. 2008 Apr;19(4):1282-94.

Burston HE, Davey M, Conibear E. Genome-wide analysis of membrane transport using yeast knockout arrays. Methods Mol. Biol. (2008) PMID 19066017

Kostelansky MS, Schluter C, Tam YY, Lee S, Ghirlando R, Beach B, Conibear E, Hurley JH. Molecular architecture and functional model of the complete yeast ESCRT-I heterotetramer. Cell 129(3):485-98. (2007) PMID 17442384

Lam KK, Davey M, Sun B, Roth AF, Davis NG, Conibear E. Palmitoylation by the DHHC protein Pfa4 regulates the ER exit of Chs3. J. Cell Biol. 174(1):19-25. (2006) PMID 16818716

Quenneville NR, Conibear E. Toward the systems biology of vesicle transport. Traffic 7(7):761-8. (2006) PMID 16787392

Canadian Institute for Health Research New Investigator Award, 2007

Michael Smith Foundation for Health Research Scholar, 2004 - 2009

Helen Burston, PhD Student
Catherine Choi, Research Assistant
Michael Davey, Research Assistant
Tanya Erb, Research Coordinator
Walden Kwong, Undergraduate Academic Assistant
Karen Lam, Research Assistant
David Lin, Research Assistant
Jeffrey Nguyen, Undergraduate Academic Assistant
Preet Pandher, Undergraduate Academic Assistant
Nicole Quenneville, PhD Student
Nandini Raghuram, Undergraduate Academic Assistant
Cayetana Schluter, Lab Manager