Dr. Kang, Seung-gu
Institution
Computational Biology Center, IBM T. J. Watson Research Center, Yorktown
Heights, NY, United States.
Presentation day
wednesday 10:00 AM
TITLE
Molecular mechanism of surface-assisted self-assembly of amyloid-like peptides
Abstract
Protein self-assembly attracted huge interests due to clinical importance in proteinaggregation
diseases, as well as potential applications for novel material design. Despites a large effort,
however, the factors governing assembly growth and morphologies seem to be often controversial due to
the delicacy between molecular systems and various environmental factors, such as surface polarity and
ionic strength. Recently, a 9-residue peptide, NH2-VGGAVVAGV-CONH2 extracted from consensus
sequences of amyloidogenic proteins was shown to assemble into a highly-ordered epitaxial structure on
both hydrophilic mica and hydrophobic highly-oriented pyrolytic graphite (HOPG) surfaces but with different
morphologies: upright conformations on mica and lying-down on HOPG. Furthermore, under high salt
concentration, the peptides at mica/water interface formed a highly-ordered multilayered nanofilaments in
highly controllable fashion, which is unusual compared to uncontrollable, disordered, amorphous
aggregates observed in other proteins in the similar condition. Applying atomistic molecular dynamics
simulations, we investigated molecular details on how these factors affect the peptide assemblies, covering
from their morphologies to the epitaxial growth mechanism. Firstly, not only surface polarity but also
crystalline lattice closely incorporate with individual peptide, as synergistically inducing a highly-optimized
parallel β-stranded arrays on mica. We also showed that hydrophobic sidechain interaction indeed drives
the longitudinal length growth, while hydrophilic backbone hydrogen bonds rather control the transversal
thickness. Finally, in raised salt concentration, we found that double-layered structures of all upright
conformations could be stabilized on mica but with anti-parallel β-stands for the upper layer, while the lower
still in the parallel conformation, which again emphasizes the importance of environmental factors like
contacting surfaces.
CV
Education and training
2002 – 2009 Ph.D. Chemistry, University of Pennsylvania, Philadelphia, PA, USA
“Probabilistic computational protein design: Advances in methodology and the incorporation of non-biological molecular components”, Prof. Jeffery G. Saven
1996 – 1998 M.S. Chemistry, Yonsei University, Seoul, Korea
1992 – 1996 B.S. Chemistry, Yonsei University, Seoul, Korea
Professional experiences
2014 – current Research Staff Member, Computational Biology Center, IBM T.J. Watson Research Center, Yorktown Heights, NY, USA
2011 – 2014 Postdoctoral Research Fellow, Computational Biology Center, IBM T.J. Watson Research Center, Yorktown Heights, NY, USA (Prof. Ruhong Zhou)
2010 – 2011 Postdoctoral Research Fellow, Department of Chemistry, University of Pennsylvania, Philadelphia, PA, USA (Prof. Jeffery G. Saven)
1998 – 2002 Full-time instructor (2nd Lieutenant) , Department of Chemistry, Korea Air Force Academy, Chungju, Korea
Literatures
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Dai, B.; Kang, S.-g.; Huynh, T.; Lei, H.; Castelli, M.; Hu, J.; Zhang, Y.; Zhou, R., Salts drive controllable multilayered upright assembly of amyloid-like peptides at mica/water interface. Proceedings of the National Academy of Sciences 2013, 110 (21), 8543-8548.
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Kang, S.-g.; Huynh, T.; Xia, Z.; Zhang, Y.; Fang, H.; Wei, G.; Zhou, R., Hydrophobic Interaction Drives Surface-Assisted Epitaxial Assembly of Amyloid-like Peptides. J. Am. Chem. Soc. 2013, 135 (8), 3150-3157.