Abstract
The aspartate and maltose responses of E. coli are mediated through a single membrane receptor, yet the responses are independent and additive. Both stimuli cause methylation of the same 4 glutamic acid residues. More extensive methylation occurs when a cell that has adapted to one stimulus is exposed to the second, or when both stimuli are added simultaneously. The degree of methylation, as well as receptor migration on two-dimensional gels, demonstrates that only one type of protein is involved, rather than two different receptors arising from differential processing of a single gene. A conformational "push-pull" mechanism in which binding of stimulus and covalent modification, producing opposing stresses, can explain these diverse results.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, Non-P.H.S.
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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ATP-Binding Cassette Transporters*
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Aspartic Acid / pharmacology*
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Bacterial Proteins / metabolism*
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Carrier Proteins / genetics
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Carrier Proteins / metabolism
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Escherichia coli / drug effects
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Escherichia coli / genetics
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Escherichia coli / metabolism*
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Escherichia coli Proteins*
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Genes
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Genes, Bacterial
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Maltose / metabolism
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Maltose / pharmacology*
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Maltose-Binding Proteins
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Methylation
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Models, Biological
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Monosaccharide Transport Proteins*
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Mutation
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Plasmids
Substances
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ATP-Binding Cassette Transporters
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Bacterial Proteins
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Carrier Proteins
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Escherichia coli Proteins
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Maltose-Binding Proteins
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Monosaccharide Transport Proteins
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maltose transport system, E coli
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Aspartic Acid
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Maltose