PMID: 127791Nov 10, 1975

Energy transduction in Escherichia coli. The role of the Mg2+ATPase

The Journal of Biological Chemistry
T Tsuchiya, B P Rosen

Abstract

Inverted membrane vesicles from strain 7, a wild type Escherichia coli K12 strain, actively transport calcium with energy supplied either by respiration or by ATP. These vesicles also have energy-linked quenching of quinacrine fluorescence. Membranes of strain 7, depleted of Mg2+ATPase by EDTA treatment, lack both activities. Membrane vesicles from strain NR70, a mutant lacking the Mg2+ATPase, show neither calcium transport nor energy-linked fluorescence quenching. Neither EDTA treatment nor genetic loss of the Mg2+atpase causes a reduction in respiration. Purified Mg2+ATPase from strain 7 can bind to EDTA-treated membrane vesicles from either strain 7 or NR70. This binding restored both calcium transport and fluorescence quenching, driven either by respiration or by ATP. Dicyclohexylcarbodiimide treatment mimics the effect of the Mg2+ATPase in the case of respiration-driven reactions. Treatment with EDTA, while not essential for the binding of the Mg2+ATPase to membrane vesicles of NR70, produced better restoration of both activities. The rate of restoration of fluorescence quenching showed a time lag which may indicate that binding of the Mg2+ATPase is a relatively slow process. Antiserum prepared against the Mg2+ATPase inhib...Continue Reading

Related Concepts

Energy Transfer
Alkalescens-Dispar Group
Calcium
Fluorescence Spectroscopy
DNA-dependent ATPase
Oxygen Consumption
Quinacrine, (S)-Isomer
Respiratory Chain
Enzyme Activation
Plasma Membrane

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