Insights into Binding of Cholera Toxin to GM1 Containing Membrane

Basu, Ipsita; Mukhopadhyay, Chaitali

doi:10.1021/la5036618

Cited by 46 publications

(49 citation statements)

References 59 publications

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“…The distribution of D of wtCTxB was best fit to three populations representing CTxB bound to 1, 2, or 3 GM1. These are consistent with simulations that show that only three of the five putative binding sites of CTxB are typically bound to GM1 (36). The diffusion rates observed here are consistent with the variety of previously published average diffusion rates (11,14,(37)(38)(39)(40)(41)(42)(43).…”

Section: Discussionsupporting

confidence: 92%

Structured clustering of the glycosphingolipid GM1 is required for membrane curvature induced by cholera toxin

Kabbani

Raghunathan

Lencer

et al. 2020

Preprint

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AB5 bacterial toxins and polyomaviruses induce membrane curvature as a mechanism to facilitate their entry into host cells. How membrane bending is accomplished is not yet fully understood but has been linked to the simultaneous binding of the pentameric B-subunit to multiple copies of their glycosphingolipid receptors. Here, we probe the toxin membrane binding and internalization mechanisms by using a combination of super-resolution and polarized localization microscopy. We show that cholera toxin subunit B (CTxB) can induce membrane curvature only when bound to multiple copies of its glycosphingolipid receptor, GM1, and the ceramide structure of GM1 is likely not a determinant of this activity as assessed in model membranes. A mutant CTxB capable of binding only a single GM1 fails to generate curvature either in model membranes or in cells and clustering the mutant CTxB-single-GM1 complexes by antibody cross-linking does not rescue the membrane curvature phenotype. We conclude that both the multiplicity and specific geometry of GM1 binding sites are necessary for the induction of membrane curvature. We expect this to be a general rule of membrane behavior for all AB5 toxins and polyomaviruses that bind glycosphingolipids to invade host cells.SIGNIFICANCE STATEMENTMembrane binding toxins demonstrate both a public health challenge and a bioengineering opportunity due to their efficient internalization into cells. These toxins multivalently bind to naturally occurring lipid receptors at the plasma membrane and initiate endocytosis. This manuscript reports the importance of structured lipid-receptor clustering for the induction of membrane bending. We also observed that the magnitude of membrane curvature was correlated to the stoichiometry of toxin-bound receptors. By identifying how these bacterial proteins initiate membrane curvature, these findings provide mechanistic insights into the early steps of pathogenic endocytosis.

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Section: Discussionsupporting

confidence: 92%

Structured clustering of the glycosphingolipid GM1 is required for membrane curvature induced by cholera toxin

Kabbani

Raghunathan

Lencer

et al. 2020

Preprint

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“…These include the blocking of the assembly of holotoxin, preventing receptor-recognition process and directly targeting the enzymatic active site in the folding, unfolding states [10][11][12]19]. Cholera toxin B-subunit is being used as a drug carrier and is also one of the medically important bacterial toxins and requires extra attention to explore its structural properties [16,24,25]. The aim and objective of this study is to gain an understanding into the structure of the CTA1 subunit, by performing MD simulations.…”

Section: Introductionmentioning

confidence: 99%

Molecular Dynamics Simulation of Cholera Toxin A-1 Polypeptide

2016

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A molecular dynamics (MD) simulation study of the enzymatic portion of cholera toxin; cholera toxin A-1 polypeptide (CTA1) was performed at 283, 310 and 323 K. From total energy analysis it was observed that this toxin is stable thermodynamically and these outcomes were likewise confirmed by root mean square deviations (RMSD) investigations. The Cα root mean square fluctuation (RMSF) examinations revealed that there are a number of residues inside CTA1, which can be used as target for designing and synthesizing inhibitory drugs, in order to inactivate cholera toxin inside the human body. The fluctuations in the radius of gyration and hydrogen bonding in CTA1 proved that protein unfolding and refolding were normal routine phenomena in its structure at all temperatures. Solvent accessible surface area study identified the hydrophilic nature of the CTA1, and due to this property it can be a potential biological weapon. The structural identification (STRIDE) algorithm for proteins was successfully used to determine the partially disordered secondary structure of CTA1. On account of this partially disordered secondary structure, it can easily deceive the proteolytic enzymes of the endoplasmic reticulum of host cells.

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“…26,27 In addition, the glycan moieties of glycosphingolipids are exploited by several bacteria and their toxins as pedestals of adhesion to the host cells. 28,29 Therefore, finding unique enzymes that modify these glycan structures is important for the future analysis of the physiological and pathological functions of complex glycosphingolipids.…”

Section: Discussionmentioning

confidence: 99%