Postdoctoral Position Available

Dan Bolon, Ph.D.

Academic Role: Assistant Professor

Faculty Appointment(s) In:
   Biochemistry and Molecular Pharmacology

The role of molecular chaperones in biology and disease.

Chaperones assist macromolecular folding and assembly processes in all cells.

The Hsp90 molecular chaperone is essential in eukaryotes and is involved in the maturation of a restricted set of substrates/clients that are involved in cell cycle progression (many kinases), aging (telomerase), cancer (kinases and steroid hormone receptors), and cystic fibrosis (CFTR). Because Hsp90 substrates are mutated in many different forms of cancer, Hsp90 has emerged as a promising target for drugs to treat a broad spectrum of cancer. Hsp90 is clearly involved in many different essential processes in both healthy and diseased cells. However, how Hsp90 affects these processes is poorly understood.

Mechanism of substrate maturation by Hsp90

A major goal of our research is to elucidate the ATPase driven conformational cycle of Hsp90 that orchestrates the dynamic assembly of Hsp90/co-chaperone/substrate complexes and the maturation of substrates to their active conformation. To probe the physical mechanism of this dynamic protein system we are developing biophysical and biochemical tools to dissect the conformation and protein-protein interactions of Hsp90 during substrate maturation. We rely on computational modeling, structural-guided mutagenesis, biochemistry and biophysical probes including FRET and circular dichroism. We correlate our in vitro investigations with in vivo studies in yeast where Hsp90 function is essential for growth. The goal of this work is to delineate the physical mechanism by which Hsp90 matures substrates including those involved in cancer progression.

Role of chaperones in preventing substrate aggregation

Hsp90 (and many other chaperones) inhibit substrate aggregation. Aggregation events are correlated with many different human diseases including Alzheimer’s disease, Amyotrophic Lateral Sclerosis (ALS), Huntington’s disease, and Creutzfeldt-Jakob disease. Understanding how chaperones prevent aggregation may lead to improved treatments of these human diseases. Aggregation occurs when the interaction energy between two or more particles is more favorable than the interaction of those particles with the surrounding solvent. We are exploring the physical properties of chaperones that enables them to bind to substrates in a manner that improves the solubility of the substrate/chaperone complex relative to free substrate.

Selected Publications

Haririnia A., Verma R., Purohit N., Twarog M.Z., Deshaies R.J., Bolon D., Fushman D. (2008) Mutations in the hydrophobic core of ubiquitin differentially affect its recognition by receptor proteins. J. Mol. Biol., 375:979-996. [abstract in Pubmed]

Wayne N., Bolon D. N. (2007) Dimerization of Hsp90 is required for in vivo function: design and analysis of monomers and dimers. J. Biol. Chem., 282:35386-35395. [abstract in Pubmed]

Bolon D. N., Grant R. A., Baker T. A., and Sauer R. T. (2005) Specificity versus stability in computational protein design. Proc. Natl. Acad. Sci. USA, 102, 12724-12729. [abstract in Pubmed]

Bolon D. N., Grant R. A., Baker T. A., and Sauer R. T. (2004) Nucleotide-dependent substrate handoff from the SspB adaptor to the AAA+ ClpXP protease. Mol. Cell, 16, 443-450. [abstract in Pubmed]

Bolon D. N., Wah D. A., Hersch G. L., Baker T. A., and Sauer R. T. (2004) Bivalent tethering of SspB to ClpXP is required for efficient substrate delivery: a protein-design study. Mol. Cell, 13, 443-449. [abstract in Pubmed]

Bolon D. N., Marcus J. S., Ross S. A., and Mayo S. L. (2003) Prudent modeling of core polar residues in computational protein design. J. Mol. Biol., 329, 611-622. [abstract in Pubmed]

Bolon D. N. and Mayo S. L. (2001) Enzyme-like proteins by computational protein design. Proc. Natl. Acad. Sci. USA, 98, 14274-14279. [abstract in Pubmed]

Bolon D. N. and Mayo S. L. (2001) Polar residues in the protein core of E. coli thioredoxin are important for fold specificity. Biochemistry, 40, 10047-10053. [abstract in Pubmed]

Reviews

Sauer, R.T., Bolon, D.N., Burton, B.M., Burton, R.E., Flynn, J.M., Grant, R.A., Hersch, G.L., Joshi, S.A., Kenniston, J.A., Levchenko, I., Neher S.B., Siddiqui, S.M., Wah, D.A. & Baker, T.A. (2004) Sculpting the proteome with AAA+ proteases and disassembly machines. Cell, 119, 9-18. [abstract in Pubmed]

Bolon D. N., Voigt C. A. and Mayo S.L. (2002) De novo design of biocatalysts. Curr. Opin. Chem. Biol., 6, 125-129. [abstract in Pubmed]

Potential Rotation Projects

Our laboratory combines biophysical, biochemical, structural, molecular and cell biological approaches to investigate how chaperones both help substrates to mature to active conformations and inhibit substrates from aggregating. Potential rotation projects are available in both of these general areas. Please contact the lab to discuss specific rotation projects in more detail .

Academic Background

Dan Bolon majored in Biology at Duke University (B.S., 1997). For Dan’s graduate work, he studied computational enzyme design with Steve Mayo at the California Institute of Technology (Ph.D. in Biochemistry and Molecular Biophysics, 2002). From 2002-2005, he trained as a postdoc with Bob Sauer in the Biology Department at the Massachusetts Institute of Technology using a variety of biochemical and biophysical techniques including X-ray crystallography, fluorescence, analytical ultracentrifugation, and protein engineering to study AAA+ proteases. Dan was awarded a NIH fellowship to support his postdoctoral studies (2004-2005). Other interests include mountain biking and baseball. Dan joined the faculty in Biochemistry and Molecular Pharmacology in September, 2005.

Office: LRB 922
Phone: 508-856-3588
Fax: 508-856-6231
E-mail: Dan.Bolon@umassmed.edu
Keywords: Protein Folding, Biophysics, Structural Biology, Biochemistry, Systems Biology

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Postdoctoral Position Available  A postdoctoral position is available in this laboratory, experience with deep sequencing and or yeast biology is desired. Contact Dr. Bolon for additional details.