Author
LeFevre, KellyIssue Date
2002Advisor
Cordes, Matthew H. J.
Metadata
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The University of Arizona.Rights
Copyright © is held by the author. Digital access to this material is made possible by the University Libraries, University of Arizona. Further transmission, reproduction or presentation (such as public display or performance) of protected items is prohibited except with permission of the author.Abstract
The Cro protein from bacteriophage λ has a dimeric mixed α+β fold which evolved from an ancestral monomeric all-α fold. Monomeric mixed α+β structures may have been intermediates in this process. A monomeric variant of λ Cro incorporating A33W and F58D mutations has been identified and characterized. These mutations involve large changes in side chain size, and were predicted by modeling to disrupt the dimer interface while increasing the thermodynamic stability of the monomer. This combination of mutations does lower the λ Cro dissociation constant by a factor of at least 1,000, while maintaining the protein's secondary structure content. The A33W and F58D mutations also increase the maximal monomer thermal stability of λ Cro by approximately 12 degrees. The A33W/F58D Cro variant shows the plausibility of monomeric mixed α+β intermediates in the evolution of λ Cro, and shows that mutations at these positions could have been critical for evolution of the dimer.Type
textThesis-Reproduction (electronic)
Degree Name
M.S.Degree Level
mastersDegree Program
Graduate CollegeMolecular and Cellular Biology