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Benjamin Glick, Ph.D.Primary: Associate Professor, Department of Molecular Genetics and Cell
Biology Secondary: Committee on Genetics |
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Education:
Research SummaryBiogenesis and dynamics
of secretory compartments, and
directed evolution of fluorescent proteins
Our main goal is to understand the processes that generate Golgi stacks. The cisternal maturation model provides a conceptual framework for studying Golgi formation. This model postulates that new Golgi elements arise at transitional ER (tER) sites, which are specialized for the production of ER-to-Golgi transport vesicles. We have obtained evidence that in budding yeasts, Golgi distribution is a consequence of tER organization. In Saccharomyces cerevisiae, Golgi cisternae are dispersed throughout the cytoplasm and the entire ER network functions as tER, whereas in Pichia pastoris, ordered Golgi stacks are located next to discrete tER sites. We are analyzing these two yeasts in parallel with vertebrate cells. Our specific approaches are: (1) To characterize S. cerevisiae mutants with defects in premitotic Golgi inheritance. We isolated S. cerevisiae mutants that fail to partition Golgi elements into small buds, and are now studying the corresponding genes. (2) To characterize tER organization and biogenesis in P. pastoris through a combination of genetics, molecular biology, video microscopy and computer simulations. P. pastoris is an ideal model organism for these studies. For example, we have labeled the P. pastoris tER with a GFP fusion protein, and are using the resulting strain to identify mutants with altered tER structures. (3) To explore tER organization and dynamics in vertebrate cells. A single vertebrate cell contains several hundred structures that resemble the tER sites present in P. pastoris. Therefore, we are exploring the dynamics and molecular components of vertebrate tER sites. These experiments are revealing evolutionarily conserved mechanisms of tER organization. A second project in the lab involves optimizing the red fluorescent protein DsRed. Like its more famous cousin GFP (green fluorescent protein), DsRed potentially has wide application as a reporter and fusion protein tag. However, wild-type DsRed suffers from several drawbacks that limit its usefulness. For example, wild-type DsRed matures very slowly, requiring more than 24 hours at 37°C to achieve maximal fluorescence. We overcame this problem by using directed evolution to create rapidly maturing DsRed variants. One such variant is now marketed commercially as DsRed-Express. Ongoing work is aimed at generating DsRed variants that will be as versatile as GFP. Selected PublicationsGlick,
B.S. and Malhotra, V.
"The curious status of
the Golgi
apparatus." Cell,
95:883-9, 1998. PubMed Citation
Rossanese, O.W., Soderholm, J., Bevis, B.J., Sears, I.B., O'Connor, J., Williamson, E.K. and Glick, B.S. "Golgi structure correlates with transitional endoplasmic reticulum organization in Pichia pastoris and Saccharomyces cerevisiae." J. Cell Biol., 145:69-81, 1999. PubMed Citation Hammond, A.T. and Glick, B.S. "Raising the speed limits for 4D fluorescence microscopy." Traffic, 1:935-40, 2000. PubMed Citation Article Hammond, A.T. and Glick, B.S. "Dynamics of transitional endoplasmic reticulum sites in vertebrate cells." Mol. Biol. Cell, 11:3013-30, 2000. PubMed Citation Article Rossanese, O.W., Reinke, C.A., Bevis, B.J., Hammond, A.T., Sears, I.B., O'Connor, J. and Glick, B.S. "A role for actin, Cdc1p, and Myo2p in the inheritance of late Golgi elements in Saccharomyces cerevisiae." J. Cell Biol.,153:47-62, 2001. PubMed Citation Soderholm, J., Bevis, B.J. and Glick, B.S. "Vector for pop-in/pop-out gene replacement in Pichia pastoris." Biotechniques, 31:306-10, 312, 2001. PubMed Citation Bevis, B.J., Hammond, A.T., Reinke, C.A. and Glick, B.S. "De novo formation of transitional ER sites and Golgi structures in Pichia pastoris." Nat. Cell Biol., 4:750-6, 2002. PubMed Citation Article Bevis, B.J. and Glick, B.S. "Rapidly maturing variants of the Discosoma red fluorescent protein,(DsRed)." Nat. Biotechnol., 20:83-7, 2002. PubMed Citation Article Glick, B.S. "Can the Golgi form de novo?" Nat. Rev. Mol. Cell Biol., 3:615-9, 2002. PubMed Citation Article Mogelsvang, S., Gomez-Ospina, N., Soderholm, J., Glick, B.S. and Staehelin, L.A. "Tomographic evidence for continuous turnover of Golgi cisternae in Pichia pastoris." Mol. Biol. Cell, 14:2277-91, 2003. PubMed Citation ArticleUpdated 10/18/07. |
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