Office: SCIE 3458
Lab: SCIE 3403-4
B.A.Sc. (Eng. Sci. 7T8) - Toronto
M.Sc. (Medical Biophysics) - Toronto
Ph.D. (Medical Biophysics) - Toronto
Postdoctoral Fellow - Fritz Haber Institute of the Max Planck Society, West Berlin
Our group is interested in the structure and dynamics of the myelin sheath of the central nervous system, in particular the family of basic proteins (MBP). These developmentally-regulated isoforms are highly post-translationally modified and translocatable, and bind multiple target proteins such as calmodulin, actin, tubulin, and SH3-domain containing proteins. What makes them fascinating objects to study is that they are multifunctional - they represent hubs in structural and signalling networks of the myelin sheath. In the healthy sheath, there is a finely-tuned equilibrium of post-translationally modified forms, each with a specific target site and set of neighbouring binding partners. In multiple sclerosis (MS), this equilibrium is disrupted, resulting in demyelination (physical disruption and autoimmune attack of the myelin sheath). The body attempts to remyelinate, but normal signalling pathways are also disrupted, and any repair is short-lived. A key to understanding this failure requires knowledge of how the myelin sheath is organised, especially the role of MBP.
A multifunctional protein requires study by a variety of approaches. Our work is based on a library of recombinant forms of these proteins. Using site-directed and deletion mutagenesis, we can focus on specific segments and assess the roles of different domains in ligand-binding. One project presently underway involves the transfection of MBP-fluorescent protein fusion constructs into cell culture of primary and immortalised oligodendrocyte lines, to investigate these proteins' associations with cellular structures such as the cytoskeleton. We use various types of microscopy, particularly electron and confocal microscopy, to define how the MBPs interact with lipid membranes, and with proteins such as calmodulin (which would regulate its activities) or SH3-containing kinases, and the cytoskeleton.
We complement our biological investigations with biochemical and biophysical approaches, particularly spectroscopic ones - fluorescence, circular dichroism (CD), electron paramagnetic resonance (EPR), along with proteomics, molecular modelling, and various other methodologies as appropriate. One of the most powerful tools to study the dynamics and interactions of conformationally flexible proteins such as MBP is nuclear magnetic resonance (NMR) spectroscopy. In this part of our work, we collaborate with Dr. Vladimir Ladizhansky and make use of the Guelph NMR Center, one of the best equipped in the country. Our recent solution NMR studies of two isoforms of MBP, the early developmental BG21, and the mature myelin 18.5 kDa MBP, have defined regions of flexibility and transient order, representing putative targets for calmodulin and other proteins. In order to determine how MBP is folded in situ in a myelin membrane complex, Dr. Ladizhansky is developing new methods of protein structure determination using solid-state NMR spectroscopy, that push the frontier of the technique.
Some of our recent publications are listed below. We welcome inquiries from students interested in biology, chemistry, or physics, and in approaching a challenging biological system, and significant medical problem, from a variety of perspectives. Almost all of the students who have done 4th year research projects with us have gone on to further study (graduate or medical school), or employment in research or industrial laboratories.
L.N. Rahman, F. McKay, M. Giuliani, A. Quirk, B.A. Moffatt, G. Harauz, J.R. Dutcher.
Interactions of Thellungiella salsuginea dehydrins TsDHN-1 and TsDHN-2 with membranes - Surface morphology and single-molecule force measurements show differential bilayer stabilization at cold and ambient temperatures, and reveal tertiary and quaternary associations. see paper
Biochimica et Biophysica Acta - Biomembranes (BBAMEM), 1828 (3, March) 967-980, 2013.
M.A.M. Ahmed, M. De Avila, E. Polverini, K. Bessonov, V.V. Bamm, G. Harauz.
Solution NMR structure and molecular dynamics simulations of murine 18.5-kDa myelin basic protein segment (S72-S107) in association with dodecylphosphocholine micelles. see paper
Biochemistry, 51 (38), 7475-7487, 2012.
D.R. Kattnig, T. Bund, J.M. Boggs, G. Harauz, D. Hinderberger.
Lateral self-assembly of 18.5-kDa myelin basic protein (MBP) charge component C1 on membranes. see paper
Biochimica et Biophysica Acta - Biomembranes (BBAMEM), 1818 (11), 2636-2647, 2012.
L.N. Rahman, G.S.T. Smith, V.V. Bamm, J.A.M. Voyer-Grant, B.A. Moffatt, J.R. Dutcher, G. Harauz.
Phosphorylation of Thellungiella salsuginea dehydrins TsDHN-1 and TsDHN-2 facilitates actin assembly and cation-induced folding. see paper
Biochemistry, 50 (44), 9587-9604, 2011.
G.S.T. Smith, M. De Avila, P.M. Paez, V. Spreuer, M.K.B. Wills, N. Jones, J.M. Boggs, G.Harauz.
Proline substitutions and threonine pseudo-phosphorylation of the SH3-ligand of 18.5 kDa myelin basic protein decrease its affinity for the Fyn-SH3-domain and alter process development and protein localization in oligodendrocytes. see paper
Journal of Neuroscience Research, online 1 September 2011.
V.V. Bamm, M. De Avila, G.S.T. Smith, M.A.M. Ahmed, G. Harauz.
Structured functional domains of myelin basic protein: Cross-talk between actin polymerization and Ca2+-dependent calmodulin interaction. see paper
Biophysical Journal, 101 (5), 1248-1256, 2011.
G.S.T. Smith, P.M. Paez, V. Spreur, C.W. Campagnoni, J.M. Boggs, A.T. Campagnoni, G. Harauz.
Classical 18.5 and 21.5 kDa isoforms of myelin basic protein inhibit calcium influx into oligodendroglial cells. see paper
Journal of Neuroscience Research, 89 (4), 467-480, 2011.
M.A.M. Ahmed, V.V. Bamm, G. Harauz, V. Ladizhansky.
Solid-state NMR spectroscopy of membrane-associated myelin basic protein - conformation and dynamics of an immunodominant epitope. see paper
Biophysical Journal, 99 (4), 1247-1255, 2010.
V.V. Bamm, M.A.M. Ahmed, G. Harauz.
Interaction of myelin basic protein with actin in the presence of dodecylphosphocholine micelles. see paper
Biochemistry, 49 (32), 6903-6915, 2010.
K. Bessonov, V.V. Bamm, G. Harauz.
Misincorporation of the proline homologue Aze (azetidine-2-carboxylic acid) into myelin basic protein. see paper
Phytochemistry, 71 (5), 502-507, 2010.
G. Harauz, V. Ladizhansky, J.M. Boggs.
Structural polymorphism and multifunctionality of myelin basic protein. see paper
Biochemistry, 48(34), 8094-8104, 2009.
G. Harauz, D.S. Libich.
The classic basic protein of myelin - conserved structural motifs and the dynamic molecular barcode involved in membrane adhesion and protein-protein interactions. see paper
Current Protein and Peptide Science, 10 (3), 196-215, 2009.
L. Homchaudhuri, E. Polverini, W. Gao, G. Harauz, J.M. Boggs.
Influence of membrane surface charge and post-translational modifications to myelin basic protein on its ability to tether the Fyn-SH3 domain to a membrane. see paper
Biochemistry, 48 (11), 2385-2393, 2009.
M.A.M Ahmed, V.V. Bamm, L. Shi, M. Steiner-Mosonyi, J.F. Dawson, L.E. Brown, G. Harauz, V. Ladizhansky.
Induced secondary structure and polymorphism in an intrinsically disordered structural linker of the central nervous system - Solid-state NMR and FTIR spectroscopy of 18.5 kDa myelin basic protein (MBP) bound to actin.
Biophysical Journal, 96 (1), 180-191, 2009.
A.A. Musse, W. Gao, L. Homchaudhuri, J.M. Boggs, G. Harauz.
Myelin basic protein as a "PI(4,5)P2-modulin" - A new biological function for a major central nervous system protein. see paper
Biochemistry, 47 (39), 10372-10382, 2008.
D.S. Libich, G. Harauz.
Backbone dynamics of the 18.5 kDa isoform of myelin basic protein reveals transient alpha-helices and a calmodulin-binding site. see paper
Biophysical Journal, 94 (12), 4847-4866, 2008.
E. Polverini, G. Rangaraj, D.S. Libich, J.M. Boggs, G. Harauz.
Binding of the proline_rich segment of myelin basic protein to SH3-domains - Spectroscopic, microarray, and modelling studies of ligand conformation and effects of post-translational modifications. see paper
Biochemistry, 47 (1), 267-282, 2008.
X. Peng, D.S. Libich, R. Janik, G. Harauz, V. Ladizhansky.
Dipolar chemical shift correlation spectroscopy for homonuclear carbon distance measurements in proteins in the solid state: application to structure determination and refinement. see paper
Journal of the American Chemical Society, 130 (1), 359-369, 2008.
L. Zhong, V.V. Bamm, M.A.M. Ahmed, G. Harauz, V. Ladizhansky.
Solid-state NMR spectroscopy of 18.5 kDa myelin basic protein reconstituted with lipid vesicles: spectroscopic characterization and spectral assignments of solvent-exposed protein fragments. see paper
Biochimica et Biophysica Acta - Biomembranes, 1768 (12), 3193-3205, 2007.
M.A.M. Ahmed, V.V. Bamm, G. Harauz, V. Ladizhansky.
The BG21 isoform of Golli myelin basic protein is intrinsically disordered with a highly flexible amino-terminal domain. see paper
Biochemistry, 46 (34), 9700-9712, 2007.
A.A. Musse, G. Harauz.
Molecular 'negativity' may underlie multiple sclerosis (MS): Role of the myelin basic protein family in the pathogenesis of MS. see paper
International Review of Neurobiology (Chapter 7 in Special Volume #79 on Neurobiology of Multiple Sclerosis", 79C, 149-172, 2007.
V.V. Bamm, M.A.M. Ahmed, V. Ladizhansky, G. Harauz.
Fluorescence, CD, and NMR spectroscopy of the recombinant BG21 isoform of murine Golli myelin basic protein. see paper
Journal of Neuroscience Research 85 (2), 272-284, 2007.
L.S. DeBruin, G. Harauz.
White matter rafting - Membrane microdomains in myelin. see paper
Neurochemical Research 32 (2), 213-228, 2007.
G. Harauz, A.A. Musse.
A tale of two citrullines - Structural and functional aspects of myelin basic protein deimination in health and disease. see paper
Neurochemical Research 32 (2), 137-158, 2007.
MBG*3350 Laboratory Methods in Molecular Biology I
MBG*3360 Laboratory Methods in Molecular Biology II
BIOC*4580 Membrane Biochemistry
BIOP*6000 Concepts in Biophysics
NEUR*6000 Principles of Neuroscience
Dr. Vladimir (Vova) Bamm (endMS Postdoctoral Fellowship)
Dr. Luna Rahman2
Dr. Kenrick Vassall (endMS Postdoctoral Fellowship)
Ms. Janine Voyer
Miguel De Avila (Ph.D./endMS Doctoral Studentship)
Sergio Jaramillo-Tatis (M.Sc.)
Ivana Komljenovic (Ph.D.)1
Agata Zienowicz (M.Sc.)
Andrew Jenkins (M.Sc.)
1 - Co-advised with Dr. Jim Davis, Physics
2 - Co-advised with Dr. John Dutcher, Physics
Erin Stephenson (4th year research project)
Some Former Members of our Laboratory
Ahmed, University of Suez, Egypt
Dr. Ian Bates, McGill University, Montréal
Dr. Lillian DeBruin, Wilfrid Laurier University, Waterloo
Dr. Christope Farès, University of Toronto
Mr. Ehsan Fayaz, Toronto
Dr. Christopher Hill, IOGEN Corporation, Ottawa
Dr. Noboru Ishiyama, University of Toronto
Mrs. Jaspreet Kaur, University of Guelph
Dr. David Libich, Lab of Chemical Physics, National Inst. of Health, Bethesda
Dr. Abdiwahab Musse, University of California at Los Angeles
Dr. Graham Smith, Montreal
Ms. Caroline Velte, Mainz, Germany