Functional Evolution of the Cro Protein Family of Transcription Factors

Persistent Link:
http://hdl.handle.net/10150/195964
Title:
Functional Evolution of the Cro Protein Family of Transcription Factors
Author:
Hall, Branwen
Issue Date:
2007
Publisher:
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:
Members of multi-specific DNA-binding protein families have evolved to specifically recognize diverse DNA site sequences. This dissertation presents evidence that the Cro protein family of helix-turn-helix transcription factors from lambdoid bacteriophages may share a conserved, limited "code" that partially governs evolution of their binding specificity. A bioinformatic study revealed six conserved sequence correlations between residues at three positions in Cro recognition helices and three base-pairs in putative cognate DNA consensus half-sites (Chapter 2). Three of these pairings correspond to sequence-specific contacts observed at the binding interface of lambda Cro and consensus operator DNA in a previously available co-crystal structure (Albright and Matthews, 1998a). In vitro mutagenesis and functional characterization was used to validate the proposed "code" (Chapter 3). Two out of three "coding" combinations acted as specificity switches in lambda Cro, though variant proteins displayed reduced binding specificity for their predicted target DNA sites. Two crystal structures of a lambda Cro variant are presented in Chapter 4, which provide insight into lambda Cro dimer flexibility. Additionally, a co-crystal structure of N15 Cro bound to consensus site DNA was determined which contains two coding residue pairs at the binding interface (Chapter 5), and a crystal structure of Xfasa1 Cro that enables future investigations into Cro functional evolution (Chapter 6). Although there are several caveats, the data are consistent with a model in which Cro proteins may indeed have evolved new binding specificities in part through simple mutations at their binding interfaces that follow a simple set of evolutionarily conserved "coding" rules. The structural and functional diversity of Cro proteins provides an exciting venue for future research into their evolution.
Type:
text; Electronic Dissertation
Keywords:
protein; DNA; Cro; evolution
Degree Name:
PhD
Degree Level:
doctoral
Degree Program:
Biochemistry & Molecular Biophysics; Graduate College
Degree Grantor:
University of Arizona
Advisor:
Cordes, Matthew H
Committee Chair:
Cordes, Matthew H

Full metadata record

DC FieldValue Language
dc.language.isoENen_US
dc.titleFunctional Evolution of the Cro Protein Family of Transcription Factorsen_US
dc.creatorHall, Branwenen_US
dc.contributor.authorHall, Branwenen_US
dc.date.issued2007en_US
dc.publisherThe University of Arizona.en_US
dc.rightsCopyright © 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.en_US
dc.description.abstractMembers of multi-specific DNA-binding protein families have evolved to specifically recognize diverse DNA site sequences. This dissertation presents evidence that the Cro protein family of helix-turn-helix transcription factors from lambdoid bacteriophages may share a conserved, limited "code" that partially governs evolution of their binding specificity. A bioinformatic study revealed six conserved sequence correlations between residues at three positions in Cro recognition helices and three base-pairs in putative cognate DNA consensus half-sites (Chapter 2). Three of these pairings correspond to sequence-specific contacts observed at the binding interface of lambda Cro and consensus operator DNA in a previously available co-crystal structure (Albright and Matthews, 1998a). In vitro mutagenesis and functional characterization was used to validate the proposed "code" (Chapter 3). Two out of three "coding" combinations acted as specificity switches in lambda Cro, though variant proteins displayed reduced binding specificity for their predicted target DNA sites. Two crystal structures of a lambda Cro variant are presented in Chapter 4, which provide insight into lambda Cro dimer flexibility. Additionally, a co-crystal structure of N15 Cro bound to consensus site DNA was determined which contains two coding residue pairs at the binding interface (Chapter 5), and a crystal structure of Xfasa1 Cro that enables future investigations into Cro functional evolution (Chapter 6). Although there are several caveats, the data are consistent with a model in which Cro proteins may indeed have evolved new binding specificities in part through simple mutations at their binding interfaces that follow a simple set of evolutionarily conserved "coding" rules. The structural and functional diversity of Cro proteins provides an exciting venue for future research into their evolution.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectproteinen_US
dc.subjectDNAen_US
dc.subjectCroen_US
dc.subjectevolutionen_US
thesis.degree.namePhDen_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineBiochemistry & Molecular Biophysicsen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorCordes, Matthew Hen_US
dc.contributor.chairCordes, Matthew Hen_US
dc.contributor.committeememberMontfort, Williamen_US
dc.contributor.committeememberLittle, Johnen_US
dc.contributor.committeememberMcEvoy, Meganen_US
dc.contributor.committeememberHorton, Nancyen_US
dc.contributor.committeememberGhosh, Indraneelen_US
dc.identifier.proquest2241en_US
dc.identifier.oclc659747412en_US
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