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Thesis Defense Announcement
To:  The George Mason University Community


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.

ABSTRACT:

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.

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