Protein translocation through the anthrax toxin transmembrane pore is driven by a proton gradient

Bryan A. Krantz, Alan Finkelstein, R. John Collier

Research output: Contribution to journalArticle

125 Citations (Scopus)

Abstract

Protective antigen (PA) from anthrax toxin assembles into a homoheptamer on cell surfaces and forms complexes with the enzymatic components: lethal factor (LF) and edema factor (EF). Endocytic vesicles containing these complexes are acidified, causing the heptamer to transform into a transmembrane pore that chaperones the passage of unfolded LF and EF into the cytosol. We show in planar lipid bilayers that a physiologically relevant proton gradient (ΔpH, where the endosome is acidified relative to the cytosol) is a potent driving force for translocation of LF, EF and the LF amino-terminal domain (LF N) through the PA63 pore. ΔpH-driven translocation occurs even under a negligible membrane potential. We found that acidic endosomal conditions known to destabilize LFN correlate with an increased translocation rate. The hydrophobic heptad of lumen-facing Phe427 residues in PA (or φ clamp) drives translocation synergistically under a ΔpH. We propose that a Brownian ratchet mechanism proposed earlier for the φ clamp is cooperatively linked to a protonation-state, ΔpH-driven ratchet acting trans to the φ-clamp site. In a sense, the channel functions as a proton/protein symporter.

Original languageEnglish (US)
Pages (from-to)968-979
Number of pages12
JournalJournal of Molecular Biology
Volume355
Issue number5
DOIs
StatePublished - Feb 3 2006

Fingerprint

Protein Transport
Protons
Cytosol
Symporters
Antigens
Transport Vesicles
Proton-Motive Force
Endosomes
Lipid Bilayers
Membrane Potentials
anthrax toxin
edema factor
Proteins

Keywords

  • Planar bilayers
  • Protein unfolding
  • Proton gradient
  • Translocase
  • Translocation

ASJC Scopus subject areas

  • Virology

Cite this

Protein translocation through the anthrax toxin transmembrane pore is driven by a proton gradient. / Krantz, Bryan A.; Finkelstein, Alan; Collier, R. John.

In: Journal of Molecular Biology, Vol. 355, No. 5, 03.02.2006, p. 968-979.

Research output: Contribution to journalArticle

Krantz, Bryan A. ; Finkelstein, Alan ; Collier, R. John. / Protein translocation through the anthrax toxin transmembrane pore is driven by a proton gradient. In: Journal of Molecular Biology. 2006 ; Vol. 355, No. 5. pp. 968-979.
@article{f80a1b1345514a77a4146750ebf3fd2d,
title = "Protein translocation through the anthrax toxin transmembrane pore is driven by a proton gradient",
abstract = "Protective antigen (PA) from anthrax toxin assembles into a homoheptamer on cell surfaces and forms complexes with the enzymatic components: lethal factor (LF) and edema factor (EF). Endocytic vesicles containing these complexes are acidified, causing the heptamer to transform into a transmembrane pore that chaperones the passage of unfolded LF and EF into the cytosol. We show in planar lipid bilayers that a physiologically relevant proton gradient (ΔpH, where the endosome is acidified relative to the cytosol) is a potent driving force for translocation of LF, EF and the LF amino-terminal domain (LF N) through the PA63 pore. ΔpH-driven translocation occurs even under a negligible membrane potential. We found that acidic endosomal conditions known to destabilize LFN correlate with an increased translocation rate. The hydrophobic heptad of lumen-facing Phe427 residues in PA (or φ clamp) drives translocation synergistically under a ΔpH. We propose that a Brownian ratchet mechanism proposed earlier for the φ clamp is cooperatively linked to a protonation-state, ΔpH-driven ratchet acting trans to the φ-clamp site. In a sense, the channel functions as a proton/protein symporter.",
keywords = "Planar bilayers, Protein unfolding, Proton gradient, Translocase, Translocation",
author = "Krantz, {Bryan A.} and Alan Finkelstein and Collier, {R. John}",
year = "2006",
month = "2",
day = "3",
doi = "10.1016/j.jmb.2005.11.030",
language = "English (US)",
volume = "355",
pages = "968--979",
journal = "Journal of Molecular Biology",
issn = "0022-2836",
publisher = "Academic Press Inc.",
number = "5",

}

TY - JOUR

T1 - Protein translocation through the anthrax toxin transmembrane pore is driven by a proton gradient

AU - Krantz, Bryan A.

AU - Finkelstein, Alan

AU - Collier, R. John

PY - 2006/2/3

Y1 - 2006/2/3

N2 - Protective antigen (PA) from anthrax toxin assembles into a homoheptamer on cell surfaces and forms complexes with the enzymatic components: lethal factor (LF) and edema factor (EF). Endocytic vesicles containing these complexes are acidified, causing the heptamer to transform into a transmembrane pore that chaperones the passage of unfolded LF and EF into the cytosol. We show in planar lipid bilayers that a physiologically relevant proton gradient (ΔpH, where the endosome is acidified relative to the cytosol) is a potent driving force for translocation of LF, EF and the LF amino-terminal domain (LF N) through the PA63 pore. ΔpH-driven translocation occurs even under a negligible membrane potential. We found that acidic endosomal conditions known to destabilize LFN correlate with an increased translocation rate. The hydrophobic heptad of lumen-facing Phe427 residues in PA (or φ clamp) drives translocation synergistically under a ΔpH. We propose that a Brownian ratchet mechanism proposed earlier for the φ clamp is cooperatively linked to a protonation-state, ΔpH-driven ratchet acting trans to the φ-clamp site. In a sense, the channel functions as a proton/protein symporter.

AB - Protective antigen (PA) from anthrax toxin assembles into a homoheptamer on cell surfaces and forms complexes with the enzymatic components: lethal factor (LF) and edema factor (EF). Endocytic vesicles containing these complexes are acidified, causing the heptamer to transform into a transmembrane pore that chaperones the passage of unfolded LF and EF into the cytosol. We show in planar lipid bilayers that a physiologically relevant proton gradient (ΔpH, where the endosome is acidified relative to the cytosol) is a potent driving force for translocation of LF, EF and the LF amino-terminal domain (LF N) through the PA63 pore. ΔpH-driven translocation occurs even under a negligible membrane potential. We found that acidic endosomal conditions known to destabilize LFN correlate with an increased translocation rate. The hydrophobic heptad of lumen-facing Phe427 residues in PA (or φ clamp) drives translocation synergistically under a ΔpH. We propose that a Brownian ratchet mechanism proposed earlier for the φ clamp is cooperatively linked to a protonation-state, ΔpH-driven ratchet acting trans to the φ-clamp site. In a sense, the channel functions as a proton/protein symporter.

KW - Planar bilayers

KW - Protein unfolding

KW - Proton gradient

KW - Translocase

KW - Translocation

UR - http://www.scopus.com/inward/record.url?scp=29444456231&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=29444456231&partnerID=8YFLogxK

U2 - 10.1016/j.jmb.2005.11.030

DO - 10.1016/j.jmb.2005.11.030

M3 - Article

VL - 355

SP - 968

EP - 979

JO - Journal of Molecular Biology

JF - Journal of Molecular Biology

SN - 0022-2836

IS - 5

ER -