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Correlated protein conformational states and membrane dynamics during attack by pore-forming toxins

Ponmalar, Ilanila I and Cheerla, Ramesh and Ayappa, K Ganapathy and Basu, Jaydeep K (2019) Correlated protein conformational states and membrane dynamics during attack by pore-forming toxins. In: PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA, 116 (26). pp. 12839-12844.

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Official URL: https://dx.doi.org/10.1073/pnas.1821897116

Abstract

Pore-forming toxins (PFTs) are a class of proteins implicated in a wide range of virulent bacterial infections and diseases. These toxins bind to target membranes and subsequently oligomerize to form functional pores that eventually lead to cell lysis. While the protein undergoes large conformational changes on the bilayer, the connection between intermediate oligomeric states and lipid reorganization during pore formation is largely unexplored. Cholesterol-dependent cytolysins (CDCs) are a subclass of PFTs widely implicated in food poisoning and other related infections. Using a prototypical CDC, listeriolysin O (LLO), we provide a microscopic connection between pore formation, lipid dynamics, and leakage kinetics by using a combination of Forster resonance energy transfer (FRET) and fluorescence correlation spectroscopy (FCS) measurements on single giant unilamellar vesicles (GUVs). Upon exposure to LLO, two distinct populations of GUVs with widely different leakage kinetics emerge. We attribute these differences to the existence of oligomeric intermediates, sampling various membrane-bound conformational states of the protein, and their intimate coupling to lipid rearrangement and dynamics. Molecular dynamics simulations capture the influence of various membrane-bound conformational states on the lipid and cholesterol dynamics, providing molecular interpretations to the FRET and FCS experiments. Our study establishes a microscopic connection between membrane binding and conformational changes and their influence on lipid reorganization during PFT-mediated cell lysis. Additionally, our study provides insights into membrane-mediated protein interactions widely implicated in cell signaling, fusion, folding, and other biomolecular processes.

Item Type: Journal Article
Additional Information: copyright for this article belongs to NATL ACAD SCIENCES
Keywords: pore-forming toxin; giant unilamellar vesicle; Forster resonance energy transfer; fluorescence correlation spectroscopy
Department/Centre: Division of Interdisciplinary Research > Centre for Biosystems Science and Engineering
Division of Mechanical Sciences > Chemical Engineering
Division of Physical & Mathematical Sciences > Physics
Depositing User: Id for Latest eprints
Date Deposited: 29 Jul 2019 06:40
Last Modified: 29 Jul 2019 06:46
URI: http://eprints.iisc.ac.in/id/eprint/63227

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