Structural map of the dicyclohexylcarbodiimide site of chloroplast coupling factor determined by resonance energy transfer.

Published

Journal Article

Fluorescence resonance energy-transfer measurements were made on the membrane-bound chloroplast coupling factor. The distances from the N,N'-dicyclohexylcarbodiimide-binding site on the membrane-bound portion of the enzyme (CF0) to the vesicle surface and to two sulfhydryl sites on the gamma-polypeptide were determined. The dicyclohexylcarbodiimide-binding site was labeled with the fluorescent species N-cyclohexyl-N'-pyrenylcarbodiimide. The vesicle surface was labeled with N-(7-nitro-2,1,3-benzoxadiazol-4-yl)phosphatidylethanolamine. Steady-state energy transfer between the fluorescent-labeled enzyme (energy donor) and varying concentrations of the ethanolamine derivative (energy acceptor) indicated that the distance of closest approach between the energy donor and the outer vesicle surface is 16-24 A. Two specific sites on the gamma-polypeptide were reacted with a coumarinylmaleimide derivative; one is a sulfhydryl that can be labeled only on the thylakoids under energized conditions (the "light" site), while the other is the disulfide site that regulates enzymatic activity. Energy-transfer measurements utilizing steady-state fluorescence and fluorescence lifetime methods indicated that the dicyclohexylcarbodiimide site is approximately 41 A from the light site and approximately 50 A from the gamma-disulfide site. These distances are used to extend the current structural model of the chloroplast coupling factor.

Full Text

Duke Authors

Cited Authors

  • Mitra, B; Hammes, GG

Published Date

  • April 4, 1989

Published In

Volume / Issue

  • 28 / 7

Start / End Page

  • 3063 - 3069

PubMed ID

  • 2525921

Pubmed Central ID

  • 2525921

International Standard Serial Number (ISSN)

  • 0006-2960

Digital Object Identifier (DOI)

  • 10.1021/bi00433a049

Language

  • eng

Conference Location

  • United States