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Structural and functional insights into prokaryotic rhomboids Open Access


Other title
prokaryotic rohmboid
X-ray crystallography
Domain swapping
Rhomboid functional assay
N-terminal domain of E. Coli GlpG
Type of item
Degree grantor
University of Alberta
Author or creator
Lazareno-Saez, Christelle
Supervisor and department
Lemieux, Joanne (Biochemistry)
Examining committee member and department
Lemieux, Joanne (Biochemistry)
Glover, Mark (Biochemistry)
Leslie, Elaine (Physiology)
McQuibban, Angus (Biochemistry, University of Toronto)
Lemire, Bernard (Biochemistry)
Department of Biochemistry

Date accepted
Graduation date
Doctor of Philosophy
Degree level
Rhomboids are a family of intramembrane serine peptidases that cleaves a peptide bond of a substrate protein in the lipid bilayer. Various cellular processes such as cell differentiation and apoptosis have been linked to rhomboids proteolytic activty. More precisely, active and inactive rhomboids have been related to wound healing, type II diabetes, as well as respiratory defects and cancer. Currently, knowledge on rhomboids is limited with only two structures of prokaryotic rhomboids being elucidated: one from Haemophilus influenzae (hiGlpG) and a partial one (membrane domain from Escherichia coli (ecGlpG)). Initial studies have proposed a model for the reaction mechanism and the access of the substrate to the buried catalytic site of rhomboids. However, the structures have raised new questions and more structural details are needed. For example, different rhomboids contain a cytosolic domain, which has been hypothesized to be involved in regulation. In fact, the structure of the full-length ecGlpG (ecGlpG-FL) containing a large N-terminal cytoplasmic domain (ecGlpG-cyto) was never solved due to its arduous purification. To date, no structural information is available for any eukaryotic rhomboids, which often contain this cytosolic domain. This thesis aims to provide a detailed investigation of the catalytic mechanism, substrate access and regulation of prokaryotic rhomboids as they represent a valuable tool to study their eukaryotic counterparts. A new structural and functional study of hiGlpG proposed a model for the access of the substrate to the active site allowing us to gain insights into the catalytic mechanism. In addition structural and functional studies on ecGlpG-cyto revealed that this domain i) does not affect the apparent kinetic parameters of the enzyme and ii) oligomerize upon domain swapping.
This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for the purpose of private, scholarly or scientific research. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.
Citation for previous publication
Cory L. Brooks, Christelle Lazareno-Saez, Jason S. Lamoureux, Michelle W. Mak and M. Joanne Lemieux. Journal of Molecular Biology. 2011;407(5):687-697.Christelle Lazareno-Saez, Elena Arutyunova, Nicolas Coquelle, M. Joanne Lemieux. Journal of Molecular Biology. 2013;425(7):1127-42.Christelle Lazareno-Saez, Cory L. Brooks, M. Joanne Lemieux. Biochemistry and Cell Biology. 2011;89(2): 216-223.

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