Cryo-electron microscopy reveals the membrane insertion mechanism of V. cholerae hemolysin |
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Authors: | Somnath Dutta Kalyan K. Banerjee |
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Affiliation: | 1. Division of Electron Microscopy, National Institute of Cholera and Enteric Diseases, P-33, C.I.T. Road, Scheme-XM, Beleghata, Kolkata, 700010, India.;2. Division of Biochemistry, National Institute of Cholera and Enteric Diseases, P-33, C.I.T. Road, Scheme-XM, Beleghata, Kolkata, 700010, India. |
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Abstract: | Vibrio cholerae hemolysin (HlyA) is a 65?kDa pore-forming toxin which causes lysis of target eukaryotic cells by forming heptameric channels in the plasma membrane. Deletion of the 15?kDa C-terminus β-prism carbohydrate-binding domain generates a 50?kDa truncated variant (HlyA50) with 1000-fold-reduced pore-forming activity. Previously, we showed by cryo-electron microscopy that the two toxin oligomers have central channels, but the 65?kDa toxin oligomer is a seven-fold symmetric structure with bowl-, ring-, and arm-like domains, whereas the 50?kDa oligomer is an asymmetric jar-like heptamer. In the present study, we determined three-dimensional(3D) structures of HlyA and HlyA50 in presence of erythrocyte stroma and observed that interaction of the 65?kDa toxin with the stroma induced a significant decrease in the height of the β-barrel oligomer with a change in conformation of the ring- and arm-like domains of HlyA. These features were absent in interaction of HlyA50 with stroma. We propose that this conformational transition is critical for membrane-insertion of the toxin. |
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Keywords: | cryo-electron microscopy Vibrio cholerae hemolysin single particle analysis pore-forming toxin |
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