Light-driven amino acid uptake in Streptococcus cremoris or Clostridium acetobutylicum membrane vesicles fused with liposomes containing bacterial reaction centers

Journal Article · Fri Apr 01 00:00:00 EST 1988 · J. Bacteriol.; (United States)

OSTI ID:7242476

Crielaard, W; Driessen, A J; Molenaar, D; Hellingwerf, K J; Konings, W N

Reaction centers of the phototrophic bacterium Rhodopseudomonas palustris were introduced as proton motive force-generating systems in membrane vesicles of two anaerobic bacteria. Liposomes containing reaction center-light-harvesting complex I pigment protein complexes were fused with membrane vesicles of Streptococcus cremoris or Clostridium acetobutylicum by freeze-thawing and sonication. Illumination of these fused membranes resulted in the generation of a proton motive force of approximately -110 mV. The magnitude of the proton motive force in these membranes could be varied by changing the light intensity. As a result of this proton motive force, amino acid transport into the fused membranes could be observed. The initial rate of leucine transport by membrane vesicles of S. cremoris increased exponentially with the proton motive force. An H+/leucine stoichiometry of 0.8 was determined from the steady-state level of leucine accumulation and the proton motive force, and this stoichiometry was found to be independent of the magnitude of the proton motive force. These results indicate that the introduction of bacterial reaction centers in membrane vesicles by the fusion procedure yields very attractive model systems for the study of proton motive force-consuming processes in membrane vesicles of (strict) anaerobic bacteria.

• Research Organization: Univ. of Groningen, Haren (Netherlands)
• OSTI ID: 7242476
• Journal Information: J. Bacteriol.; (United States), Vol. 170:4
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
AMINO ACIDS
MEMBRANE TRANSPORT
CLOSTRIDIUM
PHOTOSYNTHETIC REACTION CENTERS
STREPTOCOCCUS
CELL MEMBRANES
LEUCINE
LIPOSOMES
PHOTOSYNTHETIC MEMBRANES
PROTONS
STOICHIOMETRY
BACTERIA
BARYONS
CARBOXYLIC ACIDS
CELL CONSTITUENTS
ELEMENTARY PARTICLES
FERMIONS
HADRONS
MEMBRANES
MICROORGANISMS
NUCLEONS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANOIDS
550200* - Biochemistry