Second-chance signal transduction explains cooperative flagellar switching.

The reversal of flagellar motion (switching) results from the interaction between a switch complex of the flagellar rotor and a torque-generating stationary unit, or stator (motor unit). To explain the steeply cooperative ligand-induced switching, present models propose allosteric interactions betwe...

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Main Authors: Henry G Zot, Javier E Hasbun, Nguyen Van Minh
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2012-01-01
Series:PLoS ONE
Online Access:http://europepmc.org/articles/PMC3402542?pdf=render
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spelling doaj-69d1917d12a749a5997ed53b74aa48a82020-11-24T23:48:47ZengPublic Library of Science (PLoS)PLoS ONE1932-62032012-01-0177e4109810.1371/journal.pone.0041098Second-chance signal transduction explains cooperative flagellar switching.Henry G ZotJavier E HasbunNguyen Van MinhThe reversal of flagellar motion (switching) results from the interaction between a switch complex of the flagellar rotor and a torque-generating stationary unit, or stator (motor unit). To explain the steeply cooperative ligand-induced switching, present models propose allosteric interactions between subunits of the rotor, but do not address the possibility of a reaction that stimulates a bidirectional motor unit to reverse direction of torque. During flagellar motion, the binding of a ligand-bound switch complex at the dwell site could excite a motor unit. The probability that another switch complex of the rotor, moving according to steady-state rotation, will reach the same dwell site before that motor unit returns to ground state will be determined by the independent decay rate of the excited-state motor unit. Here, we derive an analytical expression for the energy coupling between a switch complex and a motor unit of the stator complex of a flagellum, and demonstrate that this model accounts for the cooperative switching response without the need for allosteric interactions. The analytical result can be reproduced by simulation when (1) the motion of the rotor delivers a subsequent ligand-bound switch to the excited motor unit, thereby providing the excited motor unit with a second chance to remain excited, and (2) the outputs from multiple independent motor units are constrained to a single all-or-none event. In this proposed model, a motor unit and switch complex represent the components of a mathematically defined signal transduction mechanism in which energy coupling is driven by steady-state and is regulated by stochastic ligand binding. Mathematical derivation of the model shows the analytical function to be a general form of the Hill equation (Hill AV (1910) The possible effects of the aggregation of the molecules of haemoglobin on its dissociation curves. J Physiol 40: iv-vii).http://europepmc.org/articles/PMC3402542?pdf=render
collection DOAJ
language English
format Article
sources DOAJ
author Henry G Zot
Javier E Hasbun
Nguyen Van Minh
spellingShingle Henry G Zot
Javier E Hasbun
Nguyen Van Minh
Second-chance signal transduction explains cooperative flagellar switching.
PLoS ONE
author_facet Henry G Zot
Javier E Hasbun
Nguyen Van Minh
author_sort Henry G Zot
title Second-chance signal transduction explains cooperative flagellar switching.
title_short Second-chance signal transduction explains cooperative flagellar switching.
title_full Second-chance signal transduction explains cooperative flagellar switching.
title_fullStr Second-chance signal transduction explains cooperative flagellar switching.
title_full_unstemmed Second-chance signal transduction explains cooperative flagellar switching.
title_sort second-chance signal transduction explains cooperative flagellar switching.
publisher Public Library of Science (PLoS)
series PLoS ONE
issn 1932-6203
publishDate 2012-01-01
description The reversal of flagellar motion (switching) results from the interaction between a switch complex of the flagellar rotor and a torque-generating stationary unit, or stator (motor unit). To explain the steeply cooperative ligand-induced switching, present models propose allosteric interactions between subunits of the rotor, but do not address the possibility of a reaction that stimulates a bidirectional motor unit to reverse direction of torque. During flagellar motion, the binding of a ligand-bound switch complex at the dwell site could excite a motor unit. The probability that another switch complex of the rotor, moving according to steady-state rotation, will reach the same dwell site before that motor unit returns to ground state will be determined by the independent decay rate of the excited-state motor unit. Here, we derive an analytical expression for the energy coupling between a switch complex and a motor unit of the stator complex of a flagellum, and demonstrate that this model accounts for the cooperative switching response without the need for allosteric interactions. The analytical result can be reproduced by simulation when (1) the motion of the rotor delivers a subsequent ligand-bound switch to the excited motor unit, thereby providing the excited motor unit with a second chance to remain excited, and (2) the outputs from multiple independent motor units are constrained to a single all-or-none event. In this proposed model, a motor unit and switch complex represent the components of a mathematically defined signal transduction mechanism in which energy coupling is driven by steady-state and is regulated by stochastic ligand binding. Mathematical derivation of the model shows the analytical function to be a general form of the Hill equation (Hill AV (1910) The possible effects of the aggregation of the molecules of haemoglobin on its dissociation curves. J Physiol 40: iv-vii).
url http://europepmc.org/articles/PMC3402542?pdf=render
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AT javierehasbun secondchancesignaltransductionexplainscooperativeflagellarswitching
AT nguyenvanminh secondchancesignaltransductionexplainscooperativeflagellarswitching
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