Abstract
MotA and MotB form the proton-channel complex of the proton-driven bacterial flagellar motor. A plug segment of Escherichia coli MotB suppresses proton leakage through the MotA/B complex when it is not assembled into the motor. Using a ratiometric pH indicator protein, pHluorin, we show that the proton-conductivity of a Salmonella MotA/B complex not incorporated into the motor is two orders of magnitude lower than that of a complex that is incorporated and activated. This leakage is, however, significant enough to change the cytoplasmic pH to a level at which the chemotaxis signal transduction system responds.
Copyright 2010 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Bacterial Proteins / chemistry
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Bacterial Proteins / genetics
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Bacterial Proteins / metabolism
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Bacterial Proteins / physiology*
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Bacteriological Techniques
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Cytoplasm / genetics
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Cytoplasm / metabolism
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Electric Conductivity*
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Fluorescent Dyes / metabolism
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Fluorescent Dyes / pharmacology
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Gene Expression Regulation, Bacterial
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Green Fluorescent Proteins / genetics
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Green Fluorescent Proteins / metabolism*
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Green Fluorescent Proteins / pharmacology
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Hydrogen-Ion Concentration
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Multiprotein Complexes / chemistry
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Multiprotein Complexes / metabolism
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Mutation, Missense
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Proton Pumps / chemistry
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Proton Pumps / metabolism
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Proton Pumps / physiology
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Protons
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Salmonella enterica / genetics
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Salmonella enterica / metabolism*
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Salmonella enterica / physiology
Substances
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Bacterial Proteins
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Fluorescent Dyes
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MotA protein, Bacteria
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MotB protein, Bacteria
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Multiprotein Complexes
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PHluorin
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Proton Pumps
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Protons
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Green Fluorescent Proteins