Dr. Colón received his B.S. in Chemistry from the University of Puerto Rico at Mayaguez in 1988 and received his Ph.D. in Chemistry from Texas A&M University in 1993. After postdoctoral research as an NSF Fellow with Heinrich Roder at the Fox Chase Cancer Center, Dr. Colón joined the faculty at RPI in 1997.

Molecular Recognition in Protein Oligomerization and Aggregation

My main research interests are in the biochemical field of protein folding. The main goal of my laboratory is to investigate the chemical and physical principles of molecular recognition that lead to protein folding, oligomerization, and aggregation. In particular, my research will focus on three areas: (1) the role of kinetic intermediate(s) in determining a protein's final three-dimensional structure; (2) the role of structural intermediate(s) in the formation of amyloid fibrils and other abnormal protein aggregates; and (3) studies of the folding and/or oligomerization mechanism of proteins that through defective folding or assembly might play an important role in the pathogenesis of human diseases.

Some of the techniques used include: absorbance, fluorescence, and CD spectroscopy combined with stopped-flow methods, site-directed mutagenesis, and electron microscopy.

Protein Folding

Understanding how the amino acid sequence of a protein determines its three-dimensional structure remains one of the greatest unsolved problems in biochemistry. One hypothesis is that kinetic intermediates play an important role in protein folding by directing the process along a productive pathway, and by reducing the number of conformations that a protein needs to search through to reach the native structure. In our research we use the protein Fis (factor for inversion stimulation), a small dimeric protein, as a model system to probe the significance of kinetic intermediate(s) in its folding and dimerization mechanism. We have two main experimental objectives: (1) to change the folding pathway of Fis from one where kinetic intermediate(s) are well populated to one where intermediates are not observed; and (2) to determine how the presence or absence of intermediates affects the stability of Fis and its folding and dimerization kinetics. A major goal of this work is to help better understand whether folding intermediates play an important role in directing the folding pathway of proteins or if they just occur because of the intrinsic stability or folding kinetics of individual sub-domains.

Biophysical Mechanism of Amyloid Formation

The term amyloidosis describes a series of diseases where an otherwise soluble protein or peptide adopts an abnormal conformation and deposits extracellularly as amyloid fibrils. It is widely believed that the precursor species, which assembles to form amyloid fibrils are partially folded intermediates. Protein overexpression or an increase in intermediate population as a result of single-site mutation, appears to play a critical role in amyloidosis. Nevertheless, the molecular mechanism of amyloid formation remains poorly understood. In our lab, we are studying the folding pathway of the protein serum amyloid A (SAA), whose N-terminal 76 residues deposits as amyloid fibrils as a result of inflammation in reactive amyloidosis. We are working with several mouse isoforms including, the amyloidogenic SAA2, and the non-amyloidogenic SAA1 and CE/J. The objective of this study is to explore the role of folding intermediate in SAA amyloid formation and find the key intermolecular interactions that lead to fibril assembly, especially at the early stages.

Protein Folding Defects in Human Diseases

Familial Amyotrophic lateral schlerosis (FALS, also known as Lou Gehrigs disease) is a fatal neurodegenerative disease that affects motor neurons. Around 10% of FALS involve a mutation in Cu, Zn superoxide dismutase (SOD), which catalyzes the dismutation of the superoxide radical into hydrogen peroxide and molecular oxygen. Over 63 different single-site mutations have been identified in patients with FALS, but little is known about the pathogenic mechanism. One hypothesis suggests a gain of function in SOD, perhaps a folding defect. The goal of this project is to determine whether a folding and/or association defect exists in SOD mutants that may help explain the mechanism by which they cause FALS, and determine the severity of the disease.

Chung, J., Yang, H., deBeus, M. D., Ryu, C. Y., Cho, H. and Colón, W. Cu/Zn Superoxide Dismutase Can Form Pore-like Structures. (2003) Biochemical and Biophysical Research Communications, 312, 873-876.

Cheng, C-H., Battaglioli, G., Martin, D.L., Hobart, S. A. and Colón, W. Distinctive Interactions in the Holoenzyme Formation for two Isoforms of Glutamate Decarboxylase. (2003) Biochim. Biophys. Acta, 1645, 63-71.

Wang, L., Lashuel, H.A, Walz, T. and Colón, W. Murine Apolipoprotein Serum Amyloid A in Solution Forms A Hexamer Containing A Central Channel. (2002) Proc. Natl. Acad. Sci. USA, 99, 15947-15952.

Hobart, S. A., Meinhold, D., Osuna R., and Colón W. From Two-State to Three-State: Effect of P61A Mutation on the Dynamics and Stability of the Factor for Inversion Stimulation Results in an Altered Equilibrium Denaturation Mechanism (2002) Biochemistry, 41, 13744-13754.

Hobart, S. A., Ilin S., Moriarty D. F., Osuna R., and Colón W. Equilibrium Denaturation Studies of the E. Coli Factor for Inversion Stimulation: Implications for In Vivo Function. (2002) Protein Science, 11, 1671-1680.

Colón, W. Solving the Protein Folding Problem Chemical & Engineering News, March 26, 2001, page 225.

Cheng, C-H, Colón, W., Myer, Y.P. and Martin, D.L. ATP’s Impact on the Conformation and Holoenzyme Formation in Relation to the Regulation of Brain Glutamate Decarboxylase, (2000) Archives of Biochemistry and Biophysics, 380, 285-293.

Colón, W. Analysis of Protein Structure by Solution Spectroscopy (1999) Methods in Enzymology 310, 316-340.

Colón, W., Wakem, P., Sherman, F. and Roder, H. Identification of the Predominant Non-Native Histidine Ligand of Unfolded Cytochrome c (1997) Biochemistry, 36, 12535-12541.

Roder, H. and Colón, W. Role of Structural Intermediates in Protein Folding. (1997) Current Opinion in Structural Biology, 7, 15-28.

Colón, W. and Roder, H. Kinetic Intermediates in the Formation of the Cytochrome c Molten Globule. (1996) Nature Structural Biology, 3, 1019-1025.

Colón, W., Elöve, G. E., Waken, L. P., Sherman, F. and Roder, H. Side Chain Packing of the N- and C- Terminal Helices Plays a Critical Role in the Kinetics of Cytochrome c Folding. (1996) Biochemistry, 35, 5538-5549.

Lai, Z., Colón, W. and Kelly, J.W. The Acid–Mediated Denaturation Pathway of Transthyretin Yields an Intermediate Which can Self-Assemble into Amyloid. (1996) Biochemistry, 35, 6470-6482.

McCutchen, S. L., Lai, Z., Miroy, G. J., Kelly, J.W. and Colón, W. Comparison of Lethal and Nonlethal Transthyretin Variants and Their Relationship to Amyloid Disease. (1995) Biochemistry, 34, 13527-13536.

Colón, W. and Kelly, J.W. Partial Denaturation of Transthyretin is Sufficient for Amyloid Fibril Formation In Vitro. (1992) Biochemistry, 31, 8654-8660.