Catechin-mediated restructuring of a bacterial toxin inhibits activity.
Aggregatibacter actinomycetemcomitans
/ chemistry
Bacterial Toxins
/ chemistry
Catechin
/ chemistry
Cell Membrane
/ metabolism
Cell Survival
Cholesterol
/ chemistry
Circular Dichroism
Exotoxins
/ chemistry
Humans
Leukocytes
/ metabolism
Membrane Fluidity
Microscopy, Confocal
Periodontitis
/ therapy
Protein Structure, Secondary
Surface Plasmon Resonance
THP-1 Cells
Aggregatibacter actinomycetemcomitans
Bacterial toxin
Catechins
RTX toxin
leukotoxin
Journal
Biochimica et biophysica acta. General subjects
ISSN: 1872-8006
Titre abrégé: Biochim Biophys Acta Gen Subj
Pays: Netherlands
ID NLM: 101731726
Informations de publication
Date de publication:
01 2019
01 2019
Historique:
received:
20
08
2018
revised:
12
10
2018
accepted:
15
10
2018
pubmed:
21
10
2018
medline:
17
8
2019
entrez:
21
10
2018
Statut:
ppublish
Résumé
Catechins, polyphenols derived from tea leaves, have been shown to have antibacterial properties, through direct killing of bacteria as well as through inhibition of bacterial toxin activity. In particular, certain catechins have been shown to have bactericidal effects on the oral bacterium, Aggregatibacter actinomycetemcomitans, as well as the ability to inhibit a key virulence factor of this organism, leukotoxin (LtxA). The mechanism of catechin-mediated inhibition of LtxA has not been shown. In this work, we studied the ability of six catechins to inhibit LtxA-mediated cytotoxicity in human white blood cells, using Trypan blue staining, and investigated the mechanism of action using a combination of techniques, including fluorescence and circular dichroism spectroscopy, confocal microscopy, and surface plasmon resonance. We found that all the catechins except (-)-catechin inhibited the activity of this protein, with the galloylated catechins having the strongest effect. Pre-incubation of the toxin with the catechins increased the inhibitory action, indicating that the catechins act on the protein, rather than the cell. The secondary structure of LtxA was dramatically altered in the presence of catechin, which resulted in an inhibition of toxin binding to cholesterol, an important initial step in the cytotoxic mechanism of the toxin. These results demonstrate that the catechins inhibit LtxA activity by altering its structure to prevent interaction with specific molecules present on the host cell surface. Galloylated catechins modify protein toxin structure, inhibiting the toxin from binding to the requisite molecules on the host cell surface.
Sections du résumé
BACKGROUND
Catechins, polyphenols derived from tea leaves, have been shown to have antibacterial properties, through direct killing of bacteria as well as through inhibition of bacterial toxin activity. In particular, certain catechins have been shown to have bactericidal effects on the oral bacterium, Aggregatibacter actinomycetemcomitans, as well as the ability to inhibit a key virulence factor of this organism, leukotoxin (LtxA). The mechanism of catechin-mediated inhibition of LtxA has not been shown.
METHODS
In this work, we studied the ability of six catechins to inhibit LtxA-mediated cytotoxicity in human white blood cells, using Trypan blue staining, and investigated the mechanism of action using a combination of techniques, including fluorescence and circular dichroism spectroscopy, confocal microscopy, and surface plasmon resonance.
RESULTS
We found that all the catechins except (-)-catechin inhibited the activity of this protein, with the galloylated catechins having the strongest effect. Pre-incubation of the toxin with the catechins increased the inhibitory action, indicating that the catechins act on the protein, rather than the cell. The secondary structure of LtxA was dramatically altered in the presence of catechin, which resulted in an inhibition of toxin binding to cholesterol, an important initial step in the cytotoxic mechanism of the toxin.
CONCLUSIONS
These results demonstrate that the catechins inhibit LtxA activity by altering its structure to prevent interaction with specific molecules present on the host cell surface.
GENERAL SIGNIFICANCE
Galloylated catechins modify protein toxin structure, inhibiting the toxin from binding to the requisite molecules on the host cell surface.
Identifiants
pubmed: 30342156
pii: S0304-4165(18)30332-5
doi: 10.1016/j.bbagen.2018.10.011
pmc: PMC6235716
mid: NIHMS1509885
pii:
doi:
Substances chimiques
Bacterial Toxins
0
Exotoxins
0
leukotoxin
0
Catechin
8R1V1STN48
Cholesterol
97C5T2UQ7J
Types de publication
Journal Article
Research Support, N.I.H., Extramural
Research Support, U.S. Gov't, Non-P.H.S.
Langues
eng
Pagination
191-198Subventions
Organisme : NIDCR NIH HHS
ID : K99 DE022795
Pays : United States
Organisme : NIDCR NIH HHS
ID : R00 DE022795
Pays : United States
Organisme : NIDCR NIH HHS
ID : R03 DE025275
Pays : United States
Informations de copyright
Copyright © 2018 Elsevier B.V. All rights reserved.
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