Fusion of Inverted Repeats Leads to Formation of Dicentric Chromosomes that Cause Genome Instability in Budding Yeast

Persistent Link:
http://hdl.handle.net/10150/204271
Title:
Fusion of Inverted Repeats Leads to Formation of Dicentric Chromosomes that Cause Genome Instability in Budding Yeast
Author:
Kaochar, Salma
Issue Date:
2010
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.
Embargo:
Embargo: Release after 5/3/2012
Abstract:
Large-scale changes are common in genomes, and are often associated with pathological disorders. In the work presented in this dissertation, I provide insights into how inverted repeat sequences in budding yeast fuse during replication. Fusion leads to the formation of dicentric chromosomes, a translocation, and other chromosomal rearrangements.Using extensive genetics and some molecular analyses, I demonstrate that dicentric chromosomes are key intermediates in genome instability of a specific chromosome in budding yeast. I provide three pieces of evidence that is consistent with this conclusion. First, I detect a recombination fusion junction that is diagnostic of a dicentric chromosome (using a PCR technique). Second, I show a strong correlation between the amount of the dicentric fragment and the frequency of instability of the entire chromosome. Third, I demonstrate that a mutant known to stabilize dicentric chromosomes suppress instability. Based on these observations, I conclude that dicentric chromosomes are intermediates in causing genome instability in this system.Next, we demonstrate that fusion of inverted repeats is general. Both endogenous and synthetic nearby inverted repeats can fuse. Using genetics, I also show that many DNA repair and checkpoint pathways suppress fusion of nearby inverted repeats and genome instability. Based on our analysis, we propose a novel mechanism for fusion of inverted repeats that we term `faulty template switching.'Lastly, I discuss two genes that are necessary for fusion of nearby inverted repeats. I identified a mutant of the Exonuclease 1 (Exo1) and a mutant of anaphase inhibitor securin (Pds1) that suppress nearby inverted repeat fusion and genome instability. Studies of Exo1 and Pds1 provide us with insights into the molecular mechanisms of fusion.Our finding that nearby inverted repeats can fuse to form dicentric chromosomes that lead to genome instability may have great implications. The generality of this fusion reaction raises the possibility that dicentric chromosomes formed by inverted repeats can lead to genome instability in mammalian cells, and thereby contribute to a cancer phenotype.
Type:
text; Electronic Dissertation
Keywords:
budding yeast; checkpoint; Dicentric chromosome; faulty template switch; Genome rearrangements; Inverted repeats
Degree Name:
Ph.D.
Degree Level:
doctoral
Degree Program:
Graduate College; Molecular & Cellular Biology
Degree Grantor:
University of Arizona
Advisor:
Weinert, Ted

Full metadata record

DC FieldValue Language
dc.language.isoenen_US
dc.titleFusion of Inverted Repeats Leads to Formation of Dicentric Chromosomes that Cause Genome Instability in Budding Yeasten_US
dc.creatorKaochar, Salmaen_US
dc.contributor.authorKaochar, Salmaen_US
dc.date.issued2010-
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.releaseEmbargo: Release after 5/3/2012en_US
dc.description.abstractLarge-scale changes are common in genomes, and are often associated with pathological disorders. In the work presented in this dissertation, I provide insights into how inverted repeat sequences in budding yeast fuse during replication. Fusion leads to the formation of dicentric chromosomes, a translocation, and other chromosomal rearrangements.Using extensive genetics and some molecular analyses, I demonstrate that dicentric chromosomes are key intermediates in genome instability of a specific chromosome in budding yeast. I provide three pieces of evidence that is consistent with this conclusion. First, I detect a recombination fusion junction that is diagnostic of a dicentric chromosome (using a PCR technique). Second, I show a strong correlation between the amount of the dicentric fragment and the frequency of instability of the entire chromosome. Third, I demonstrate that a mutant known to stabilize dicentric chromosomes suppress instability. Based on these observations, I conclude that dicentric chromosomes are intermediates in causing genome instability in this system.Next, we demonstrate that fusion of inverted repeats is general. Both endogenous and synthetic nearby inverted repeats can fuse. Using genetics, I also show that many DNA repair and checkpoint pathways suppress fusion of nearby inverted repeats and genome instability. Based on our analysis, we propose a novel mechanism for fusion of inverted repeats that we term `faulty template switching.'Lastly, I discuss two genes that are necessary for fusion of nearby inverted repeats. I identified a mutant of the Exonuclease 1 (Exo1) and a mutant of anaphase inhibitor securin (Pds1) that suppress nearby inverted repeat fusion and genome instability. Studies of Exo1 and Pds1 provide us with insights into the molecular mechanisms of fusion.Our finding that nearby inverted repeats can fuse to form dicentric chromosomes that lead to genome instability may have great implications. The generality of this fusion reaction raises the possibility that dicentric chromosomes formed by inverted repeats can lead to genome instability in mammalian cells, and thereby contribute to a cancer phenotype.en_US
dc.typetexten_US
dc.typeElectronic Dissertationen_US
dc.subjectbudding yeasten_US
dc.subjectcheckpointen_US
dc.subjectDicentric chromosomeen_US
dc.subjectfaulty template switchen_US
dc.subjectGenome rearrangementsen_US
dc.subjectInverted repeatsen_US
thesis.degree.namePh.D.en_US
thesis.degree.leveldoctoralen_US
thesis.degree.disciplineGraduate Collegeen_US
thesis.degree.disciplineMolecular & Cellular Biologyen_US
thesis.degree.grantorUniversity of Arizonaen_US
dc.contributor.advisorWeinert, Teden_US
dc.contributor.committeememberNagy, Lisaen_US
dc.contributor.committeememberDieckmann, Carolen_US
dc.contributor.committeememberBurd, Gailen_US
dc.contributor.committeememberParker, Royen_US
dc.identifier.proquest10902-
dc.identifier.oclc659754786-
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