Cytotoxic Helix-Rich Oligomer Formation by Melittin and Pancreatic Polypeptide |
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Authors: | Pradeep K. Singh Dhiman Ghosh Debanjan Tewari Ganesh M. Mohite Edmund Carvalho Narendra Nath Jha Reeba S. Jacob Shruti Sahay Rinti Banerjee Amal K. Bera Samir K. Maji |
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Affiliation: | 1. Department of Biosciences and Bioengineering, IIT Bombay, Mumbai, Maharashtra, India.; 2. Department of Biotechnology, IIT Madras, Chennai, Tamil Nadu, India.; Children''s Hospital of Pittsburgh, University of Pittsburgh Medical Center, UNITED STATES, |
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Abstract: | Conversion of amyloid fibrils by many peptides/proteins involves cytotoxic helix-rich oligomers. However, their toxicity and biophysical studies remain largely unknown due to their highly dynamic nature. To address this, we chose two helical peptides (melittin, Mel and pancreatic polypeptide, PP) and studied their aggregation and toxicity. Mel converted its random coil structure to oligomeric helical structure upon binding to heparin; however, PP remained as helix after oligomerization. Interestingly, similar to Parkinson’s associated α-synuclein (AS) oligomers, Mel and PP also showed tinctorial properties, higher hydrophobic surface exposure, cellular toxicity and membrane pore formation after oligomerization in the presence of heparin. We suggest that helix-rich oligomers with exposed hydrophobic surface are highly cytotoxic to cells irrespective of their disease association. Moreover as Mel and PP (in the presence of heparin) instantly self-assemble into stable helix-rich amyloidogenic oligomers; they could be represented as models for understanding the biophysical and cytotoxic properties of helix-rich intermediates in detail. |
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