The Evolution of Allosteric Regulation in Chorismate Mutase
Open Access
- Author:
- Nelson, Evan
- Area of Honors:
- Chemistry
- Degree:
- Bachelor of Science
- Document Type:
- Thesis
- Thesis Supervisors:
- David D Boehr, Thesis Supervisor
Elizabeth A Elacqua, Thesis Honors Advisor - Keywords:
- Allostery
Enzyme
Regulation
Chorismate mutase
Protein
Protein NMR - Abstract:
- Allostery, or “action at a distance,” is important for the function of many enzymes, and can be thought of as the ways in which proteins communicate with their environment and express their cellular needs. Here, we use Saccharomyces cerevisiae chorismate mutase (ScCM) as a model system for studying allostery. ScCM is a homodimeric enzyme that is allosterically inhibited by tyrosine, allosterically activated by tryptophan, and displays substrate cooperativity. ScCM has sequence and structural similarity to other fungal and plant chorismate mutase enzymes, although not all of these enzymes are allosterically regulated in the same fashion. To gain information about the sequence determinants of allosteric regulation, I employed bioinformatic analyses to study sequence differences between fungal and plant chorismate mutases. However, the high degree of similarity between these enzymes did not provide much insight into their different allosteric regulation patterns. These results suggested that differences in allosteric regulation were not encoded only according to conserved amino acid residues, and more in-depth analysis (e.g. amino acid covariance analysis) may be required. I also further explored the ScCM T226I variant, which previous studies indicated was “locked” in the more active “R” conformation, using nuclear magnetic resonance spectroscopy to gain more insight into the solution characteristics of this variant. These studies indicated that contrary to the results of previous studies, the introduction of the T226I mutation causes structural changes (e.g. misfolding) to the ScCM protein that are observable in NMR spectra.