Emily Gesner
Department of Biochemistry
Supervisor: Dr. Andrew MacMillan
Originally from Fredericton, NB I completed a
BSc. (Honours) with a double major in Biology
and Chemistry at the University of New
Brunswick, Fredericton. At UNB I began my
scientific career through a Federal Student Work
Exchange Program (FSWEP) position with
Agriculture and Agri-Food Canada at the Potato
Research Centre in Fredericton. I worked for
three summers analyzing nitrogen levels in soil,
plant, and leaf samples in various crop yield
studies and collecting plant, soil, and green
house gas samples from potato, wheat and
barley fields testing the effect of fertilizer
composition on plant yield. I truly enjoyed this on hands on experience with science which lead me to
pursue my PhD at the University of Alberta.
Under the supervision of Dr Andrew MacMillan in the Biochemistry Department, I undertook a
number of projects studying small regulatory RNAs in a variety of species including Drosophila, C.
elegans, Humans, and Bacteria. My experience in the MacMillan laboratory has been an exciting
period in my development as a researcher and I have gained invaluable skills relevant to the in vitro
analysis of biological systems.
In bacteria and archaea, small RNAs derived from clustered, regularly interspaced, short palindromic
repeat (CRISPR) genetic loci are involved in an adaptable and heritable gene-silencing pathway
which can target viruses, plasmids, and transposons. This system allows bacteria to acquire resistance
to viral infection by incorporating short invading DNA sequences into their genome as CRISPR
spacer elements separated by short repeat sequences. Processing of long primary transcripts (precrRNAs) containing these repeats by an RNA endonuclease generates the mature effector RNAs that
interfere with phage gene expression.
The goal of this project was to understand the mechanism and structural details of the Thermus
thermophilus CRISPR Cse3 endonuclease which is essential for the processing of the CRISPR
transcript into mature effector CRISPR RNAs (crRNAs). High resolution X-ray structures of Cse3
bound to repeat RNAs model both the pre- and post-cleavage complexes associated with crRNA
processing. These structures establish the molecular basis of specific CRISPR RNA recognition and
suggest the mechanism for generation of effector RNAs responsible for gene-silencing. This project
was not accomplished alone and I would like to acknowledge Dr. Matthew Schellenberg, the co-lead
author on this paper, for his significant contribution to this work. I would also like to thank the other
contributing authors, Erin Garside, Mark George, and my supervisor Dr Andrew MacMillan.
I graduated from my PhD program in June, 2010 and am currently employed at Resverlogix Corp., a
biotechnology company located in Calgary that develops drugs that reduce heart disease and
arthrosclerosis by increasing the levels of HDLc (the "good cholesterol").