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Erin
R. Murphy, Ph.D.
Assistant Professor of Bacteriology
Department of Biomedical Sciences
murphy@oucom.ohiou.edu
135 Life Sciences Building
740-597-3061 |
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Research Interests: Bacterial Pathogenesis
Research in my laboratory is designed to investigate
the ways by which bacteria regulate the expression
of specific genes in response to environmental
conditions encountered within the human host.
Specifically, I am interested in understanding the
molecular mechanisms controlling the expression of
virulence-associated genes in the pathogenic
bacterium Shigella dysenteriae.
A current focus in the laboratory is the
investigation of temperature-dependent regulation of
shuA, a gene encoding the S. dysenteriae
outer-membrane heme receptor. Like nearly all
living organisms, S. dysenteriae must balance
the essential need for iron against the potential
toxicity of the element. One way the bacterium
achieves this delicate balance is by tightly
regulating the expression and activity of various
iron acquisition systems. Heme represents a
potentially rich source of nutrient iron for S.
dysenteriae during infection within the human
host. Preliminary data suggests that temperature
influences the expression of shuA. Regulation
in response to temperature is a common mechanism
utilized by S. dysenteriae to control the
expression of factors required for infection within
the human host. Experimentation is underway to
investigate the role of a global
temperature-sensitive regulator (H-NS) and DNA
sequence within the extended 5’ un-translated region
of the shuA mRNA molecule in mediating the
observed temperature-dependent regulation of shuA
expression.
A second focus in the laboratory is to further
characterize the role of the small RNA (sRNA) RyhB
in regulating the expression of S. dysenteriae
virulence factors. Bacterial sRNA molecules are
short RNA molecules that function to influence the
expression of specific gene targets. The study of
bacterial sRNA molecules, their role in pathogenesis
and their mechanisms of action is a rapidly
expanding area of scientific investigation. One of
the most well characterized bacterial sRNA molecules
is RyhB. Initially characterized in Escherichia
coli, RyhB has been shown to regulate the
expression of specific genes by binding to and
destabilizing target mRNA molecules. Recently, RyhB
has been identified in S. dysenteriae and
shown to regulate the expression of virulence
factors in this human intracellular pathogen.
Specifically, S. dysenteriae RyhB has been
shown to repress the expression of virB, a
gene essential for infection by this bacterium. RyhB-dependent
repression of virB expression is unique in
that it appears to be occurring via a previously
uncharacterized mechanism. Experiments are ongoing
in the laboratory to investigate the molecular
mechanism of RyhB-dependent regulation of virB
expression. |
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