My research career began as an undergraduate at the University of Calgary in the lab of Dr. Ken Stevenson where I studied the halophilic archaebacterium Haloferax volcanii. Studying an organism from this ancient kingdom piqued my interest in the biochemical origins of life and the RNA World hypothesis, which postulates that life on Earth began with catalytic RNA or ribozymes. I then decided to pursue a PhD studying group II introns in the lab of Dr. Steven Zimmerly at the University of Calgary. Group II introns are self-splicing ribozymes that can excise themselves from pre-mRNAs. What I also found very intriguing about group II introns was that they could function as retroelements by associating with intron-encoded reverse transcriptases (RT) and invade DNA targets. My first graduate project involved studying the evolutionary relationship between group II intron RNA structures and their cognate RTs (1). In the course of this project, I discovered a novel class of group II introns called the IIC introns. Around the same time, Dr. Francois Michel also determined the unusual secondary structure of these introns (2). At ~450 nt in length, IIC introns were the smallest known autocatalytic group II introns. Furthermore, phylogenetic analysis of IIC RTs revealed them to be the most primitive (3). This led me to biochemically characterize a IIC intron from the halophilic eubacterium Bacillus halodurans (4). Currently, I am working as a postdoctoral fellow in the lab of Dr. Anna Marie Pyle at Yale University where I am using x-ray crystallography to gain insight into the structure and function of group II introns. We have just recently succeeded in determining the crystal structure of an intact group IIC intron from the halotolerant alkaliphile Oceanobacillus iheyensis (5). This structure provides the first view into the active site of a group II intron. In addition, the core of the group II intron and the spliceosome are conserved and this structure provides a biochemical rationale for this observation. This reinforces the notion that group II introns and the spliceosome share a common ancestor. Going forward, my continuing focus will be to study evolutionary relationships using a combination of phylogenetics, biochemistry, and structural biology.

1. Toor N, Hausner G, Zimmerly S. Coevolution of group II intron RNA structures with their intron-encoded reverse transcriptases. RNA. 2001 Aug;7(8):1142-52.
2. Granlund M, Michel F, Norgren M. Mutually exclusive distribution of IS1548 and GBSi1, an active group II intron identified in human isolates of group B streptococci. J Bacteriol. 2001 Apr;183(8):2560-9.
3. Rest JS, Mindell DP. Retroids in archaea: phylogeny and lateral origins. Mol Biol Evol. 2003 Jul;20(7):1134-42. Epub 2003 May 30.
4. Toor N, Robart AR, Christianson J, Zimmerly S. Self-splicing of a group IIC intron: 5' exon recognition and alternative 5'splicing events implicate the stem-loop motif of a transcriptional terminator. Nucleic Acids Res. 2006;34(22):6461-71. Epub 2006 Nov 27.
5. Toor N, Keating KS, Taylor SD, Pyle AM. Crystal structure of a self-spliced group II intron. Science. 2008 Apr 4;320(5872):77-82.