Stander Symposium abstract book - University of Dayton

POSTER SESSION 1
plicate genes bab1 and bab2 that encode the Bab1 and Bab2 transcription factor proteins. These proteins block pigment development as they
repress the expression of genes needed for the pigment metabolic pathway. For Drosophila melanogaster, the dorsal cuticle covering the posterior
abdominal segments of males, but not females, is fully pigmented. This sexual dimorphism stems from the absence of Bab1 and Bab2 expression
from these segments in males. Interestingly though, females from different geographic populations vary in the extent of pigmentation ranging
from a near total absence to a more male-like pattern. I hypothesized that differences in Bab1 and Bab2 expression would exist between females
with different extents of abdominal pigmentation. For my thesis I have employed in situ hybridization and immunohistochemical methods to test
this hypothesis through observations of the mRNA and protein products respectively. My results raise new questions regarding how the expression
patterns of duplicate genes evolve.
Do Trends in Bacterial Replication Restart Pathways Depend on the Presence of
Primosome Protein DnaT?
Presenter(s): Linda Berg
Advisor(s): Matthew E Lopper
Chemistry - Graduate Research
Throughout the life of a cell, the process of DNA replication is challenged by factors that can bring about damage to the DNA, which ultimately
leads to a halt in DNA replication and, if not corrected, cell death. Bacteria solve this problem with a mechanism called DNA replication restart. DNA
replication restart is catalyzed by primosome proteins which are well-studied in the model organism, E. coli. However, not all bacteria encode the
full complement of primosome proteins, suggesting that differences might exist in DNA replication restart pathways among diverse bacteria. N.
gonorrhoeae, for example, lacks a DnaT homolog, but DnaT is encoded by E. coli and is thought to affect interactions between primosome protein
PriB and single-stranded DNA. This raises the question of how a bacterium might compensate for lack of a primosome protein, such as DnaT, that
provides otherwise essential functions in some bacteria. Since N. gonorrhoeae PriB has a weak interaction with single-stranded DNA, as opposed
to the strong interaction between PriB and single-stranded DNA in E. coli, we hypothesized that the presence of a DnaT homolog could be used
to predict the affinity with which a bacterial PriB would bind single-stranded DNA. Binary interactions between PriB and single-stranded DNA of
two bacteria, Klebsiella pneumoniae (which encodes a DnaT homolog) and Yersinia enterocolitica (which lacks a DnaT homolog) were analyzed.
Both K. pneumoniae and Y. enterocolitica have a high affinity PriB:single-stranded DNA interaction with dissociation constants of ~62 nM and
~84 nM, respectively. Thus, the presence of DnaT cannot be used to predict affinities of binary interactions between PriB and single-stranded DNA.
However, the experimentally measured binding constants combined with amino acid sequence alignments of the PriB homologs have led to the
definition of parameters for high affinity binary interactions between PriB and single-stranded DNA.
Inhibition of the PriA and PriB Primosome Proteins of the Neisseria gonorrhoeae
Replication Restart Pathway.
Presenter(s): Hayley E Ward
Advisor(s): Matthew E Lopper
Chemistry - Honors Thesis
DNA damage that occurs in bacterial cell DNA can lead to cell death by inhibiting the replication of genetic material. Bacteria, such as Neisseria
gonorrhoeae, have developed a method to avoid cell death due to premature termination of DNA replication using a DNA replication restart pathway.
Previous research has determined that there are two proteins, PriA and PriB, that play an important roll in the replication restart pathway.
Collectively, these enzymes bind to the DNA and facilitate reloading of the replication machinery in order to initiate replication without an origin
sequence. The proposed study will look for possible inhibitors to the function of PriA and PriB and will also explore the method through which
these inhibitors function. These inhibitors could potentially be developed into novel antibiotics against N. gonorrhoeae.
35