Gloss, Lisa M.
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Research Interests
The Gloss lab uses biochemical and biophysical methods to characterize protein macromolecular assemblies, focusing on three systems: 1) folding of oligomeric histone proteins; 2) assembly of the core nucleosome; 3) haloadaptation of enzymes from the archae extreme halophiles. The overarching goal of these studies is to understand how protein sequence encodes structure, stability, assembly and function.

Histone folding. In the past two decades many protein folding studies have focused on small, single domain monomers, which fold by two-state kinetic mechanisms, with no transiently populated intermediates. These experimental studies, coupled with advanced computational approaches, have suggested that folding intermediates may be kinetic traps which hinder productive folding. Focusing on the canonical histone hand-shake dimerization motif, we are providing an essential extension of protein folding studies to oligomeric proteins, and asking how does a protein’s primary structure encode its secondary, tertiary and quaternary structure and the mechanism of efficient formation of intra- and intermolecular contacts to yield the native three-dimensional structure. We have found a positive correlation between the population of kinetic intermediates and faster dimerization and folding, suggesting the hypothesis that, for larger proteins, kinetic intermediates accelerate productive folding. We are testing this hypothesis with WT and mutant forms of the eukaryotic heterodimers, H2A-H2B and H3-H4, and two archael homodimeric histones, hMfB and hPyA1

Nucleosome assembly. The nucleosome core particle (NCP) is the fundamental repeating unit of DNA compaction into chromosome. The dynamic nature of the NCP is an important regulator of many DNA-templated chemistries: transcription, replication, recombination and repair. Misregulation of these chemistries leads to a range of diseases, particularly cancer. Our long-term goal is to understand how histone alternations (sequence differences in histone variants or post-translational modifications) and interactions (with histone chaperones or chromatin remodeling complexes) regulate NCP stability, assembly and dynamics. Our current focus is development and utilization of protein-protein Förster Resonance Energy Transfer (FRET) system to monitor the equilibrium and kinetic processes of H2A-H2B dimer dissociation from the H3-H4 tetramer & DNA binary complex.

Halophilic and mesophilic dihydrofolate reductases. The goal of this research is to determine the sequence determinants that permit function of enzymes from the archae extreme halophiles at high ionic strength (2 to 4 M) and correspondingly lower water activity. The results will elucidate how the aqueous solvent and ionic cosolutes influence the stability, solubility and catalytic activity of enzymes—information that is essential for the engineering of better biocatalysts for a range of biotechnological applications. We use the well-characterized E. coli dihydrofolate reductase (ecDHFR) as our mesophilic model for comparison to the DHFRs from Haloferax volcanii (hvDHFR1 and hvDHFR2). The ionic strength dependence of several properties of the WT and mutant DHFRs are examined: equilibrium stability, substrate affinity, catalytic activity, flexibility by NMR (in collaboration with Dr. John K. Young at Mississippi State University) and enzyme solubility.

Publications (2000 - Current)

Hoch, Duane A., Stratten, Jessica J. & Gloss, Lisa M. Protein-protein Förster Resonance Energy Transfer Analysis of Nucleosome Core Particles Containing H2A and H2A.Z. J. Mol. Biol. in press.

Placek, Brandon J., Harrison, L. Nicole, Villers, Brooke M. & Gloss, Lisa M. (2005) The H2A.Z-H2B dimer is very unstable in comparison to the dimer with H2B formed by the dominant H2A variant. Protein Science. 14(2): 514-522.

Placek, Brandon J. & Gloss, Lisa M. (2005) Three-state kinetic folding mechanism of the H2A/H2B histone heterodimer: the N-terminal tails affect the transition state between a dimeric intermediate and the native dimer. J. Mol. Biol. 345: 827-836.

Topping, Traci B. & Gloss, Lisa M. (2004) The differential stabilities of histones from mesophilic, thermophilic and hyperthermophilic archae are manifested in both the rates of folding and unfolding. J. Mol. Biol. 342: 247-260.

Banks, Douglas D. & Gloss, Lisa M. (2004) Folding of the H3-H4 dimer and assembly into the (H3-H4)2 tetramer. Protein Science. 13: 1304-1316.

Topping, Traci B., Hoch, Duane A. & Gloss, Lisa M. (2004) Folding mechanism of FIS, the intertwined, helical Factor for Inversion Stimulation. J. Mol. Biol. 335: 1065-1081.

Banks, Douglas D. & Gloss, Lisa M. (2003) The equilibrium folding of the core histones: The H3-H4 tetramer is less stable than the H2A-H2B dimer. Biochemistry. 42: 6827-39.

Gloss, Lisa M. & Placek, Brandon J. (2002) The effects of salt on the stability of the H2A-H2B dimer. Biochemistry. 41: 14951-59.

Placek, Brandon, J. & Gloss, Lisa M. (2002) The N-terminal tails of the H2A-H2B affect dimer structure and stability. Biochemistry. 41: 14960-68.

Wright, Donna B., Banks, Douglas D., Lohman, Jeremy R., Hilsenbeck, Jaqueline L. & Gloss, Lisa M. (2002) Comparison of the effects of salt on the activity and stability of Escherichia coli and Haloferax volcanii dihydrofolate reductases. J. Mol. Biol. 323: 327-344.

Gloss, Lisa M., Simler, B. Robert & Matthews, C. Robert. (2001) Rough energy landscapes in protein folding: Dimeric E. coli Trp repressor folds through three parallel channels. J. Mol. Biol. 312: 1121-1134.

Mevarech, Moshe, Frodo, Felix, Gloss, Lisa M. (2000) Halophilic Enzymes: Proteins with a Grain of Salt. Biophysical Chemistry. 86: 155-164.