A reaction-induced fourier transform-infrared spectroscopic study of the lactose permease. A transmembrane potential perturbs carboxylic acid residues

Jason S. Patzlaff, Robert J Brooker, Bridgette A. Barry

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

In chemiosmotic coupling, a transmembrane ion gradient is used as the source of energy to drive reactions. This process occurs in all cells, but the microscopic mechanism is not understood. Here, Escherichia coli lactose permease was used in a novel spectroscopic method to investigate the mechanism of chemiosmotic coupling in secondary active transporters. To provide a light-triggered electrochemical gradient, bacteriorhodopsin was co-reconstituted with the permease, and reaction-induced Fourier transform-infrared spectra were obtained from the co-reconstituted samples. The bacteriorhodopsin contributions were subtracted from these data to give spectra reflecting permease conformational changes that are induced by an electrochemical gradient. Positive bands in the 1765-1730 cm-1 region are attributable to carboxylic acid residues in the permease and are consistent with changes of pK(a), protonation state, or environment. This is the first direct information concerning gradient-induced structural changes in the permease at the single amino acid level. Ultimately, these structural changes facilitate galactoside binding and may be involved in the storage of free energy.

Original languageEnglish (US)
Pages (from-to)28695-28700
Number of pages6
JournalJournal of Biological Chemistry
Volume275
Issue number37
DOIs
StatePublished - Sep 15 2000

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Membrane Transport Proteins
Fourier Analysis
Carboxylic Acids
Membrane Potentials
Fourier transforms
Infrared radiation
Bacteriorhodopsins
Galactosides
Proton-Motive Force
Protonation
Escherichia coli
Free energy
Ions
Light
Amino Acids
lactose permease

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A reaction-induced fourier transform-infrared spectroscopic study of the lactose permease. A transmembrane potential perturbs carboxylic acid residues. / Patzlaff, Jason S.; Brooker, Robert J; Barry, Bridgette A.

In: Journal of Biological Chemistry, Vol. 275, No. 37, 15.09.2000, p. 28695-28700.

Research output: Contribution to journalArticle

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