Download the full-sized PDF of Characterization of oligomeric state of prokaryotic rhomboid proteasesDownload the full-sized PDF



Permanent link (DOI):


Export to: EndNote  |  Zotero  |  Mendeley


This file is in the following communities:

Graduate Studies and Research, Faculty of


This file is in the following collections:

Theses and Dissertations

Characterization of oligomeric state of prokaryotic rhomboid proteases Open Access


Other title
oligomerization rhomboid protease
Type of item
Degree grantor
University of Alberta
Author or creator
Sampath Kumar, Padmapriya
Supervisor and department
Dr. Joanne Lemieux, Dept. of Biochemistry
Examining committee member and department
Dr. Joel Weiner, Dept. of Biochemistry
Dr. Richard Fahlman, Dept. of Biochemistry
Dr. Emmanuelle Cordat, Dept. of Physiology
Department of Biochemistry

Date accepted
Graduation date
Master of Science
Degree level
Rhomboid proteases are a remarkable class of intramembrane enzymes that carry out cleavage of transmembrane substrates within or proximal to the lipid bilayer. These proteases have been linked to several human diseases such as cancer, diabetes and early-onset blindness. They are also involved in diverse processes including quorum sensing and cell differentiation in bacteria. To better understand the mechanisms underlying the proteolytic action and function of these proteases, we have focussed on investigating its regulation. In this thesis, the concept of oligomerization as a possible mode of regulation is examined. To assess the oligomeric state of three prokaryotic rhomboid proteases from Haemophilus influenza (hiGlpG), Escherichia coli (ecGlpG) and Bacillus subtilis (YqgP), sedimentation equilibrium analysis was carried out. The predominant species for the three rhomboid proteases was observed to be dimeric. To examine the effect of the membrane domain alone on dimerization, hiGlpG, the simplest form of rhomboid representing the core of six transmembrane domains, was studied further. Gel filtration, crosslinking and functional assay demonstrate that hiGlpG is dimeric and functional in dodecylmaltoside detergent solution. More importantly, co-immunoprecipitation studies establish that the dimer is present in the lipid bilayer suggesting a physiological dimer. Overall these results indicate that rhomboids form oligomers which are facilitated by the membrane domain. This thesis also investigates the physiological role of ecGlpG rhomboid from E. coli. The potential of E. coli TatA as a substrate for ecGlpG is examined using an in vitro functional assay. Additionally, affinity pull-down and co-immunoprecipitation techniques are performed to identify possible substrates for this rhomboid.
Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of these terms. The author reserves all other publication and other rights in association with the copyright in the thesis and, except as herein before provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.
Citation for previous publication
Padmapriya Sampathkumar, Michelle W. Mak, Sarah J. Fischer-Witholt, Emmanuel Guigard, Cyril M. Kay, M. Joanne Lemieux. 2012 Biochim Biophys Acta 1818(12): 3090-3097

File Details

Date Uploaded
Date Modified
Audit Status
Audits have not yet been run on this file.
File format: pdf (Portable Document Format)
Mime type: application/pdf
File size: 3071820
Last modified: 2015:10:22 06:13:16-06:00
Filename: Sampath Kumar_Padmapriya_Fall 2012.pdf
Original checksum: 00f4b844c05b29a8eae31df8ecfb509d
Well formed: false
Valid: false
Status message: Invalid page tree node offset=882966
Status message: Unexpected error in findFonts java.lang.ClassCastException: edu.harvard.hul.ois.jhove.module.pdf.PdfSimpleObject cannot be cast to edu.harvard.hul.ois.jhove.module.pdf.PdfDictionary offset=2998429
Status message: Invalid Annotation list offset=2998429
Status message: Invalid outline dictionary item offset=3018431
Activity of users you follow
User Activity Date