The 2.4 Å Crystal Structure of Cholera Toxin B Subunit Pentamer: Choleragenoid

Zhang, Rong Guang; Westbrook, Mary L.; Westbrook, Edwin M.; Scott, David; Otwinowski, Zbyszek; Maulik, Prakas R.; Reed, Robert A.; Shipley, G. Graham

doi:10.1006/jmbi.1995.0455

Cited by 116 publications

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“…This toxin is responsible for the severe diarrhea, causing deaths of hundreds of thousands of people in the developing world [1]. The cholera toxin is a heterohexameric protein consisting of one A-subunit and five B-subunits (AB 5 ) [2,3]. Each B-subunit contains 103 amino acid residues that are spread among two α-helices and ten β-strands [2,4,5].…”

Section: Introductionmentioning

confidence: 99%

“…The cholera toxin is a heterohexameric protein consisting of one A-subunit and five B-subunits (AB 5 ) [2,3]. Each B-subunit contains 103 amino acid residues that are spread among two α-helices and ten β-strands [2,4,5]. Six of the β-strands form two sets of three-stranded antiparallel sheet [2].…”

Section: Introductionmentioning

confidence: 99%

“…Each B-subunit contains 103 amino acid residues that are spread among two α-helices and ten β-strands [2,4,5]. Six of the β-strands form two sets of three-stranded antiparallel sheet [2]. The overall fold consists of six antiparallel β-strands forming a closed β-barrel, capped by an α-helix between the fourth and fifth strands [2].…”

Section: Introductionmentioning

confidence: 99%

“…Six of the β-strands form two sets of three-stranded antiparallel sheet [2]. The overall fold consists of six antiparallel β-strands forming a closed β-barrel, capped by an α-helix between the fourth and fifth strands [2]. The most striking architectural feature of the AB 5 toxin is the presence of a central pore or channel that runs along the 5-fold axis of the B5 assembly, forming a ring-like structure [2,6].…”

Section: Introductionmentioning

confidence: 99%

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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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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Molecular Dynamics Simulation of Cholera Toxin A-1 Polypeptide

2016

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“…The receptor-binding, non-toxic B-subunits of both CT and LT form circular oligomers consisting of five identical, noncovalently associated polypeptides, each with a molecular mass of Ϸ11.7 kDa. The 103 amino acids of CT B-subunits (CTB) and human LT B-subunits (LTB) share 80% homology (Domenighini et al, 1995) and their threedimensional structures are practically indistinguishable (Merritt et al, 1994a;Sixma et al, 1992;Zhang et al, 1995). Despite this close similarity, the two toxins differ significantly in their receptor-binding specificities.…”

Section: Introductionmentioning

confidence: 99%

Structural basis for differential receptor binding of cholera and Escherichia coli heat‐labile toxins: influence of heterologous amino acid substitutions in the cholera B‐subunit

Bäckström

Shahabi

Johansson

et al. 1997

Molecular Microbiology

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SummaryThe closely related B-subunits of cholera toxin (CTB) and Escherichia coli heat-labile enterotoxin (LTB) both bind strongly to GM1 ganglioside receptors but LTB can also bind to additional glycolipids and glycoproteins. A number of mutant CT B-subunits were generated by substituting CTB amino acids with those at the corresponding positions in LTB. These were used to investigate the influence of specific residues on receptor-binding specificity. A mutated CTB protein containing the first 25 residues of LTB in combination with LTB residues at positions 94 and 95, bound to the same extent as native LTB to both delipidized rabbit intestinal cell membranes, complex glycosphingolipids (polyglycosylceramides) and neolactotetraosylceramide, but not to non-GM1 intestinal glycosphingolipids. In contrast, when LTB amino acid substitutions in the 1-25 region were combined with those in the 75-83 region, a binding as strong as that of LTB to intestinal glycosphingolipids was observed. In addition, a mutant LTB with a single Gly-33→Asp substitution that completely lacked affinity for both GM1 and non-GM1 glycosphingolipids could still bind to receptors in the intestinal cell membranes and to polyglycosylceramides. We conclude that the extra, non-GM1 receptors for LTB consist of both sialylated and non-sialylated glycoconjugates, and that the binding to either class of receptors is influenced by different amino acid residues within the protein.

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