April 2011

Document Type


Degree Name



Dept. of Biochemistry and Molecular Biology


Oregon Health & Science University


This thesis examines the biochemical functions of the family of Carboxyl-terminal Binding Proteins (CtBP). CtBPs are co-repressors that exert their repressive effects by interacting with coenzymes, DNA-binding transcription factors, and chromatin interacting complexes. CtBPs are implicated in essential developmental processes and cancer biology and represent an important class of multifunctional biological molecules. This work employs two distinct biologically relevant in vivo assays utilizing the Drosophila form of CtBP to examine the essential requirements for coordinating short-range repression during embryogenesis. In addition, biochemical characterizations and in vitro assays increase the understanding of distinct biochemical domains within CtBP family members and the roles they play in transcriptional regulation and invertebrate development. In order to address the ongoing issue of the relative importance of dinucleotide binding, putative dehydrogenase enzyme activity, and oligomeric state of an active CtBP protein, we examined wild type and mutant forms of the Drosophila CtBP in the Drosophila embryo where it normally plays a well understood biological function. Specifically we established an assay to monitor short-range repression at the eve locus by inserting DNA elements of our own making into a dCtBP null embryo. With these assays we determined that short-range repression is dependent on a CtBP which retains the ability to bind to dinucleotide but can still function in the absence of dehydrogenase activity. The requirement of dinucleotide binding is most likely due to an inability to form homodimers at the site of repression. The reliability of our in vivo data is high not only because of the system in which we evaluated activity, but each of our mutant proteins was assessed for unwanted deleterious effects on the overall protein and/or disruption of biological activities associated with other CtBP functional domains.




School of Medicine



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