Candidate: Moushimi Amaya
Program: Master of Science in Biology
Date: Thursday April 19, 2012
Time: 11:30 a.m.
Place: George Mason University, Prince William campus
Bull Run Hall, Room 247
Thesis Chair: Dr. Monique van Hoek
Title: "THE PRENYLATION STATUS OF FRANCISELLA TULARENSIS PROTEIN IN HUMAN CELLS"
A copy of the thesis
is on reserve
in the Johnson Center
Library, Fairfax campus.
The thesis will not be read at the meeting, but should be
read
in advance. All members of the George Mason University community are
invited
to
attend.Francisella tularensis, the causative
agent of tularemia, can potentially be used as a bioweapon due to its
highly
infectious nature and inhalation of as little as 10 organisms to cause
onset of
the disease. As part of the infective
cycle of F. tularensis, the bacterium
may release proteins into the cytoplasm of the host cell.
These proteins can be post translationally
modified by the host cell machinery. For
example, a bacterial protein may be prenylated by the host cell
prenyltransferase. Prenylation requires
the presence of a CAAX motif on the C-terminal region of the target
protein. A bioinformatics program was
used to predict F. tularensis
proteins that are most likely to undergo prenylation. It
was determined that only one protein with
a molecular mass of 13kDa and unknown function may be prenylated. This study set out to experimentally
determine the prenylation state of this protein in human embryonic
kidney
cells. Western blotting analyses
indicated that the protein is indeed expressed in transfected HEK293T
cells. However, an immunoblot prepared to
detect
prenylated proteins in cell lysates was unable to detect this protein. The prenylation event was thus inconclusive. Protein fractionation indicated that our
protein of interest was primarily localized in the cytosolic portion of
transfected whole cell extracts. This
suggested that our protein was not prenylated.
Growth assays of bacteria with mutations in the genes were
performed. However, independently, we showed
that this
protein was not a required gene for intracellular replication. Further analysis to elucidate the
functionality of this protein is required to deduce if this Francisella
protein could be a candidate
virulence gene.
###