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L W Adler

Publications and source records attributed to L W Adler.

6 recordsLinked to original sources
PubMed1977

Functional mosaicism of membrane proteins in vesicles of Escherichia coli.

Membrane vesicles of Escherichia coli prepared by osmotic lysis of lysozyme ethylenediaminetetracetate (EDTA) spheroplasts have approximately 60% of the total membrane-bound reduced nicotinamide adenine dinucleotide (NADH) dehydrogenase (ED 1.6.99.3) and Mg2+-adenosine triphosphatase (ATPase) (EC 3.6.1.3) activities exposed on the outer surface of the inner membrane. Absorption of these vesicles with antiserum prepared against the purified soluble Mg2+-ATPase resulted in agglutination of approximately 95% of the inner membrane vesicles, as determined by dehydrogenase activity, and about 50% of the total membrane protein. The unagglutinated vesicles lacked all dehydrogenase activity and may consist of outer membrane. Lysozyme-EDTA vesicles actively transported calcium ion, using either NADH or adenosine 5'-triphosphate (ATP) as energy source. However, neither D-lactate nor reduced phenazine methosulfate energized calcium uptake, suggesting that the observed calcium uptake was not due to a small population of everted vesicles. Transport of calcium driven by either NADH or ATP was inhibited by simultaneous addition of D-lactate or reduced phenazine methosulfate. Proline transport driven by D-lactate oxidation was inhibited by either NADH oxidation or ATP hydrolysis. These results suggest that the portion of the total population of vesicles capable of active transport, i.e., the inner membrane vesicles, are functionally a homogeneous population but cannot be categorized as either right-side-out or everted, since activities normally associated with only one side of the inner membrane can be found on both sides of the membrane of these vesicles. Moreover, the data indicate that oxidation of NADH or hydrolysis of ATP by externally localized NADH dehydrogenase or Mg2+-ATPase establishes a protonmotive force of the opposite polarity from that established through D-lactate oxidation.

Adenosine Triphosphatases↗
PubMed1976

Properties of Escherichia coli mutants with alterations in Mg2+-adenosine triphosphatase.

A mutant Escherichia coli, selected for resistance to the antibiotic neomycin, was unable to utilize nonfermentable carbon sources for growth. Two strains were selected from this mutant on the basis of their ability to grow utilizing succinate as a carbon source. All three strains had approximately equal amounts of the Mg2+-adenosine triphosphatase (ATPase) (EC 3.6.1.3) protein, but the activity of the enzyme differed in each strain. The Mg2+-ATPase from each of the three strains lost activity upon solubilization and appeared to undergo rapid dissociation once solubilized. This dissociation is similar to that described for the wild type after cold exposure.

Adenosine Triphosphatases↗
PubMed1975

The maintenance of the energized membrane state and its relation to active transport in Escherichia coli.

1. An ATPase mutant of Escherichia coli and two partial revertants of that mutant were examined for the ability to generate a high energy membrane state with D-lactate or ATP, as measured by the quenching of the fluorescent dye quinacrine. 2. All three strains showed reductions in the aerobically-driven quenching of fluorescence compared to the wild type, but the reduction could be reversed by the addition of eitherN,N'-dicyclohexylcarbodiimide or the crude soluble ATPase of the wild type. 3. The mutant exhibited a decreased ability to accumulate sugars and amino acids and showed an increased permeability to protons. 4. One partial revertant showed a slight increase in active transport and a slight decrease in proton permeability. 5. The other partial revertant showed a large increase in transport ability and a large decrease in proton permeability. 6. A model is proposed in which the conformation of the Mg-2+-ATPase is important in the utilization of energy derived from the electron transport chain and this function is independent of the catalytic activity of the Mg-2+-ATPase.

Adenosine Triphosphatases↗