Oral Presentation The 4th Prato Conference on Pore Forming Proteins 2018

Structural basis and functional implications of the membrane pore-formation mechanism of Vibrio cholerae cytolysin (#28)

Kausik Chattopadhyay 1
  1. Indian Institute of Science Education and Research Mohali, Mohali, PUNJAB, India

Vibrio cholerae cytolysin (VCC) is a prominent member in the family of bacterial ß-barrel pore-forming proteins (ß-PFPs). VCC acts by forming transmembrane heptameric ß-barrel pores, thereby leading to the permeabilization of the target eukaryotic cell membranes. In spite of following the overall general scheme of the membrane pore-formation process of the bacterial ß-PFPs, structure-function mechanism of VCC highlights several unique features, functional implications of which still remain obscure. For example, VCC harbors two lectin-like domains that are not documented in the archetypical ß-PFPs. Also, membrane-interaction mechanism of VCC appears to involve a complex cross-talk between the protein and the membrane components, exact description of which remains unclear. Our ongoing research is focused toward understanding the mechanistic basis of the membrane pore-formation process of VCC, and its functional implications in the context of the host cellular responses and immunity. Toward exploring the membrane-interaction mechanism of VCC, we have shown that VCC employs a specific structural motif to recognize the phospholipid head-groups of the membrane lipid bilayer. In the absence of such recognition, membrane-bound form of VCC is unable to execute the functional pore-formation mechanism. Our study also reveals that the membrane-binding and pore-forming efficacy of VCC is critically regulated by the membrane cholesterol. VCC also exhibits a unique lectin-like activity that not only facilitates the efficient membrane-binding, but also regulates the oligomeric pore-formation mechanism. Through our studies, we have also elucidated the discrete steps of the membrane pore-formation process of VCC, which involve formation of the structurally distinct pre-pore intermediates. Finally, we have also explored the role of VCC in triggering the host cellular responses, particularly in the context of the host innate immune cells.

  1. Kathuria, R., and Chattopadhyay, K. (2018) Vibrio cholerae cytolysin: Multiple facets of the membrane interaction mechanism of a β-barrel pore-forming toxin. IUBMB Life. 70(4):260-266.
  2. Rai, A. K., and Chattopadhyay, K. (2016) Revisiting the oligomerization mechanism of Vibrio cholerae cytolysin, a beta-barrel pore-forming toxin. Biochem. Biophys. Res. Com, 474 (3), 421-427.
  3. Rai. A. K., Kundu, N., and Chattopadhyay, K. (2015) Physicochemical constraints of elevated pH affect efficient membrane interaction and arrest an abortive membrane-bound oligomeric intermediate of the beta-barrel pore-forming toxin Vibrio cholerae cytolysin. Archives of Biochemistry and Biophysics. 583, 9-17.
  4. Rai, A. K., and Chattopadhyay, K. (2015) Revisiting the membrane interaction mechanism of a membrane-damaging β-barrel pore-forming toxin Vibrio cholerae cytolysin. Molecular Microbiology, 97(6), 1051-1062.
  5. Khilwani, B., Mukhopadhaya, A.*, and Chattopadhyay, K.* (2015) Transmembrane Oligomeric form of Vibrio cholerae Cytolysin Triggers TLR2/TLR6-dependent Pro-inflammatory Responses in Monocytes and Macrophages. Biochemical Journal, 466 (1), 147-161. [*Joint Corresponding Authors].
  6. Rai, A. K., and Chattopadhyay, K. (2014) Trapping of Vibrio cholerae Cytolysin in the Membrane-bound Monomeric State Blocks Membrane Insertion and Functional Pore Formation by the Toxin. J. Biol. Chem, 289 (24), 16978-16987.
  7. Paul, K. and Chattopadhyay, K. (2014) Pre-pore oligomer formation by Vibrio cholerae cytolysin: Insights from a truncated variant lacking the pore-forming pre-stem loop. Biochem. Biophys. Res. Com., 443 (1), 189-193.
  8. Rai, A. K.*, Paul, K.*, and Chattopadhyay, K. (2013) Functional mapping of the lectin activity site on the β-Prism domain of Vibrio cholerae cytolysin: implications for the membrane pore-formation mechanism of the toxin. J. Biol. Chem, 288 (3), 1665-1673. (*These authors contributed equally to this work).
  9. Paul, K. and Chattopadhyay, K. (2012) Single point mutation in Vibrio cholerae cytolysin compromises membrane pore-formation mechanism of the toxin. FEBS Journal, 279 (21), 4039-4051.
  10. Paul, K. and Chattopadhyay, K. (2011) Unfolding distinguishes the Vibrio cholerae cytolysin precursor from the mature form of the toxin. Biochemistry, 50 (19), 3936-3945.