β-GALACTOSIDE TRANSPORT IN BACTERIAL MEMBRANE PREPARATIONS: ENERGY COUPLING VIA MEMBRANE-BOUND D-LACTIC DEHYDROGENASE
01 Aug 1970-Proceedings of the National Academy of Sciences of the United States of America (National Academy of Sciences)-Vol. 66, Iss: 4, pp 1190-1198
TL;DR: The findings indicate that the beta-galactoside uptake system is coupled to the membrane-bound D-lactic dehydrogenase via an electron transport chain but does not involve oxidative phosphorylation.
Abstract: The transport of β-galactosides by isolated membrane preparations from Escherichia coli strains containing a functional y gene is markedly stimulated by the conversion of D-lactate to pyruvate. The addition of D-lactate to these membrane preparations produces a 19-fold increase in the initial rate of uptake and a 10-fold stimulation of the steady-state level of intramembranal lactose or thiomethylgalactoside. Succinate, DL-α-hydroxybutyrate, and L-lactate partially replace D-lactate, but are much less effective; ATP and P-enolpyruvate, in addition to a number of other metabolites and cofactors, do not stimulate lactose transport by the vesicles. Lactose uptake by the membrane preparations in the presence of D-lactate requires oxygen, and is blocked by electron transport inhibitors and proton conductors; however, uptake is not significantly inhibited by high concentrations of arsenate or oligomycin. Furthermore, the P-enolpyruvate-P-transferase system is not involved in β-galactoside transport by the E. coli membrane vesicles. The findings indicate that the β-galactoside uptake system is coupled to the membrane-bound D-lactic dehydrogenase via an electron transport chain but does not involve oxidative phosphorylation.
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TL;DR: Preliminary analysis of the phospholipid composition of the isolated fractions of Salmonella typhimurium showed significant quantitative differences in the relative distribution of the major glycerophosphatides.
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TL;DR: Energy Transductions in Mitochondria and the Role of the Membrane in Motility, Bacteriocins and the Energized State are studied.
Abstract: INTRODUCTION ............................................................ A NOTE ONTERMINOLOGY. ENERGY TRANSDUCTIONS IN MITOCHONDRIA ......................... Theories of Energy Conservation ............................................ Chemical coupling hnpothesis ............................................. Conformational coupling .................................................. Chemiosmotic hypothesis ................................................ Point and Counterpoint ..................................................... Permeability of the mitochondrial membrane to protons .................... Vectorial organization of respiratory catalysts ............................. Proton extrusion and the generation of a membrane potential ............... The coupling device: ATPase and ion translocation ........................ Uncoupling and proton conduction ........................................ Fluorescent molecules as probes of the energized state ...................... Metabolite Transport by Mitochondria ...................................... Accumulation of calcium .................................................. Accumulation of potassium ............................................... Transport of phosphate and substrate anions .............................. Summary: Energy Transductions in Mitochondria ........................... ENERGY TRANSFORMATIONS IN BACTERIAL MEMBRANES............ Structural Basis ........................................................... Oxidative Phosphorylation .................................................. General features of respiration and phosphorylation ........................ Coupling factors: the role of ATPase ...................................... Nature of phosphorylating particles from bacterial membranes ............. Coupling of respiration to phosphorylation ................................. Photosynthetic Phosphorylation ............................................. Coupling of Metabolism to Transport ........................................ Transport systems and carriers ........................................... Group translocation ...................................................... Kinetic approach to energy coupling ....................................... Coupling of transport to the respiratory chain in membrane vesicles. Ion gradients and energy coupling ......................................... Role of the Membrane in Motility ............................................ Bacteriocins and the Energized State ........................................ SUMMARY AND PROSPECT .............................................. LITERATURE CITED ....................................................... 172 174 175 175 176 176 177 180 180 180 181 182 183 184 185 185 186 188 189 190 191 193 193 195 196 199 200 201 201 202 205 207 210 214 215 216 216
491 citations
TL;DR: The data imply that the antimicrobial activity of glycinol, glyceollin, and coumestrol are due to a general interaction with the bacterial membrane, which is different from that of the other phytoalexins examined.
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