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A J Driessen

Publications and source records attributed to A J Driessen.

160 records · Page 9Linked to original sources
PubMed1988

Effect of cholesterol on the branched-chain amino acid transport system of Streptococcus cremoris.

The effect of cholesterol on the activity of the branched-chain amino acid transport system of Streptococcus cremoris was studied in membrane vesicles of S. cremoris fused with liposomes made of egg yolk phosphatidylcholine, soybean phosphatidylethanolamine, and various amounts of cholesterol. Cholesterol reduced both counterflow and proton motive force-driven leucine transport. Kinetic analysis of proton motive force-driven leucine uptake revealed that the Vmax decreased with an increasing cholesterol/phospholipid ratio while the Kt remained unchanged. The leucine transport activity decreased with the membrane fluidity, as determined by steady-state fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene incorporated into the fused membranes, suggesting that the membrane fluidity controls the activity of the branched-chain amino acid carrier.

Amino Acids, Branched-Chain↗
PubMed1988

Sodium-dependent transport of neutral amino acids by whole cells and membrane vesicles of Streptococcus bovis, a ruminal bacterium.

Streptococcus bovis JB1 cells were able to transport serine, threonine, or alanine, but only when they were incubated in sodium buffers. If glucose-energized cells were washed in potassium phosphate and suspended in potassium phosphate buffer, there was no detectable uptake. Cells deenergized with 2-deoxyglucose and incubated in sodium phosphate buffer were still able to transport serine, and this result indicated that the chemical sodium gradient was capable of driving transport. However, when the deenergized cells were treated with valinomycin and diluted into sodium phosphate to create both an artificial membrane potential and a chemical sodium gradient, rates of serine uptake were fivefold greater than in cells having only a sodium gradient. If deenergized cells were preloaded with sodium (no membrane potential or sodium gradient), there was little serine transport. Nigericin and monensin, ionophores capable of reversing sodium gradients across membranes, strongly inhibited sodium-dependent uptake of the three amino acids. Membrane vesicles loaded with potassium and diluted into either lithium or choline chloride were unable to transport serine, but rapid uptake was evident if sodium chloride was added to the assay mixture. Serine transport had an extremely poor affinity for sodium, and more than 30 mM was needed for half-maximal rates of uptake. Serine transport was inhibited by an excess of threonine, but an excess of alanine had little effect. Results indicated that S. bovis had separate sodium symport systems for serine or threonine and alanine, and either the membrane potential or chemical sodium gradient could drive uptake.

Alanine↗
PubMed1987

Mechanism of energy coupling to entry and exit of neutral and branched chain amino acids in membrane vesicles of Streptococcus cremoris.

The energetics of neutral and branched chain amino acid transport by membrane vesicles from Streptococcus cremoris have been studied with a novel model system in which beef heart mitochondrial cytochrome c oxidase functions as a proton-motive force (delta p) generating system. In the presence of reduced cytochrome c, a large delta p was generated with a maximum value at pH 6.0. Apparent H+/amino acid stoichiometries (napp) have been determined at external pH values between 5.5 and 8.0 from the steady state levels of accumulation and the delta p. For L-leucine napp (0.8) was nearly independent of the pH. For L-alanine and L-serine napp decreased from 0.9-1.0 at pH 5.5 to 0-0.2 at pH 8.0. The napp for the different amino acids decreased with increasing external amino acid concentration. At pH 6.0, first order rate constants for amino acid exit (kex) under steady state conditions for L-leucine, L-alanine, and L-serine were 1.1-1.3, 0.084, and 0.053 min-1, respectively. From the pH dependence of kex it is concluded that amino acid exit in steady state is the sum of two processes, pH-dependent carrier-mediated amino acid exit and pH-independent passive diffusion (external leak). The first order rate constant for passive diffusion increased with increasing hydrophobicity of the side chain of the amino acids. As a result of these processes the kinetic steady state attained is less than the amino acid accumulation ratio predicted by thermodynamic equilibrium. The napp determined from the steady state accumulation represents, therefore, a lower limit. It is concluded that the mechanistic stoichiometry (n) for L-leucine, L-alanine, and L-serine transport most likely equals 1.

Amino Acid Transport Systems↗
PubMed1987

Arginine transport in Streptococcus lactis is catalyzed by a cationic exchanger.

Streptococcus lactis metabolizes arginine via the arginine deiminase pathway to ornithine, CO2, NH3, and ATP. The translocation of arginine and ornithine has been studied using membrane vesicles of galactose/arginine-grown cells of S. lactis fused with cytochrome c oxidase proteoliposomes by the freeze/thaw--sonication procedure earlier described. In the presence of reduced cytochrome c the fused membranes rapidly accumulate ornithine. Addition of arginine releases accumulated ornithine. Rapid uncoupler-insensitive exchange between external arginine and internal ornithine is seen at rates that are at least 60-fold higher than the rate of protonmotive force-driven arginine translocation. This arginine:ornithine exchange activity was reconstituted in proteoliposomes after solubilization of S. lactis membranes with octyl beta-D-glucopyranoside. These proteoliposomes catalyze a one-to-one exchange between arginine and ornithine. The arginine:ornithine exchange system is the first exchange system for cationic metabolites found in bacteria. Translocation of arginine via this system does not require metabolic energy obtained by arginine metabolism.

Antiporters↗
PubMed1987

Transport of branched-chain amino acids in membrane vesicles of Streptococcus cremoris.

The kinetics, specificity, and mechanism of branched-chain amino acid transport in Streptococcus cremoris were studied in a membrane system of S. cremoris in which beef heart mitochondrial cytochrome c oxidase was incorporated as a proton motive force (delta p)-generating system. Influx of L-leucine, L-isoleucine, and L-valine can occur via a common transport system which is highly selective for the L-isomers of branched chain amino acids and analogs. The pH dependency of the kinetic constants of delta p-driven L-leucine transport and exchange (counterflow) was determined. The maximal rate of delta p-driven transport of L-leucine (Vmax) increased with increasing internal pH, whereas the affinity constant increased with increasing external pH. The affinity constant for exchange (counterflow) varied in a similar fashion with pH, whereas Vmax was pH independent. Further analysis of the pH dependency of various modes of facilitated diffusion, i.e., efflux, exchange, influx, and counterflow, suggests that H+ and L-leucine binding and release to and from the carrier proceed by an ordered mechanism. A kinetic scheme of the translocation cycle of H+-L-leucine cotransport is suggested.

Amino Acids, Branched-Chain↗
PubMed1987

Regulation of arginine-ornithine exchange and the arginine deiminase pathway in Streptococcus lactis.

Streptococcus lactis metabolizes arginine by the arginine deiminase (ADI) pathway. Resting cells of S. lactis grown in the presence of galactose and arginine maintain a high intracellular ornithine pool in the absence of arginine and other exogenous energy sources. Addition of arginine results in a rapid release of ornithine concomitant with the uptake of arginine. Subsequent arginine metabolism results intracellularly in high citrulline and low ornithine pools. Arginine-ornithine exchange was shown to occur in a 1-to-1 ratio and to be independent of a proton motive force. The driving force for arginine uptake in intact cells is supplied by the ornithine and arginine concentration gradients formed during arginine metabolism. These results confirm studies of arginine and ornithine transport in membrane vesicles of S. lactis (A. J. M. Driessen, B. Poolman, R. Kiewiet, and W. N. Konings, Proc. Natl. Acad. Sci. USA, 84:6093-6097). The activity of the ADI pathway appears to be affected by the internal concentration of (adenine) nucleotides. Conditions which lower ATP consumption (dicyclohexylcarbodiimide, high pH) decrease the ADI pathway activity, whereas uncouplers and ionophores which stimulate ATP consumption increase the activity. The arginine-ornithine exchange activity matches the ADI pathway most probably by adjusting the intracellular levels of ornithine and arginine. Regulation of the ADI pathway and the arginine-ornithine exchanger at the level of enzyme synthesis is exerted by glucose (repressor, antagonized by cyclic AMP) and arginine (inducer). An arginine/ornithine antiport was also found in Streptococcus faecalis DS5, Streptococcus sanguis 12, and Streptococcus milleri RH1 type 2.

Adenine Nucleotides↗
PubMed1987

Neutral amino acid transport by membrane vesicles of Streptococcus cremoris is subject to regulation by internal pH.

The pH dependence of transport of the neutral amino acids L-serine and L-alanine by membrane vesicles of Streptococcus cremoris have been studied in detail. The rates of four modes of facilitated diffusion (e.g., influx, efflux, exchange, and counterflow) of L-serine and L-alanine increase with increasing H+ concentration. Rates of artificially imposed electrical potential across the membrane (delta psi)-driven transport of L-serine and L-alanine show an optimum at pH 6 to 6.5. Under similar conditions, delta psi- and pH gradient across the membrane (delta pH)-driven transport of L-leucine is observed within the pH range studied (pH 5.5 to 7.5). The effect of ionophores on the uptake of L-alanine and L-serine has been studied in membrane vesicles of S. cremoris fused with proteoliposomes containing beef heart mitochondrial cytochrome c oxidase as a proton motive force (delta p)-generating system (Driessen et al., Proc. Natl. Acad. Sci. USA 82:7555-7559, 1985). An increase in the initial rates of L-serine and L-alanine uptake is observed with decreasing pH, which is not consistent with the pH dependency of delta p. Nigericin, an ionophore that induced a nearly complete interconversion of delta pH into delta psi, stimulated both the rate and the final level of L-alanine and L-serine uptake. Valinomycin, an ionophore that induced a collapse of delta psi with a noncompensating increase in delta pH, inhibited L-alanine and L-serine uptake above pH 6.0 more efficiently than it decreased delta p. Experiments which discriminate between the effects of the internal pH and the driving force (delta pH) on solute transport indicate that at high internal pH the transport systems for L-alanine and L-serine are inactivated. A unique relation exists between the internal pH and the initial rate of uptake of L-serine and L-alanine with an apparent pK of 7.0. The rate of L-alanine and L-serine uptake decreases with increasing internal pH. The apparent complex relation between the delta p and transport of L-alanine and L-serine can be explained by a regulatory effect of the internal pH on the activity of the L-serine and L-alanine carriers.

Alanine↗
PubMed1987

Membrane systems in which foreign proton pumps are incorporated.

Detailed information about the role of the proton-motive force in solute transport has often been obtained from studies in model systems such as membrane vesicles. For many bacteria, such studies have been hampered by the lack of a good proton-motive force generating system in these model systems. Recently this problem has been solved by the development of procedures to incorporate foreign proton pumps in membrane vesicles derived from bacteria. This improved model system has been used for studies on the role of the proton-motive force in solute transport in fermentative bacteria and yeasts. Important applications can be found in studies of many energy-transducing systems in membranes which lack a suitable proton pump.

Bacteria↗
PubMed1986

Calcium transport in membrane vesicles of Streptococcus cremoris.

Rightside-out membrane vesicles of Streptococcus cremoris were fused with proteoliposomes containing the light-driven proton pump bacteriorhodopsin by a low-pH fusion procedure reported earlier [Driessen, A.J.M., Hellingwerf, K.J. & Konings, W.N. (1985) Biochim. Biophys. Acta 808, 1-12]. In these fused membranes a proton motive force, interior positive and acid, can be generated in the light and this proton motive force can drive the uptake of Ca2+. Collapsing delta psi with a concomitant increase in delta pH stimulates Ca2+ uptake while dissipation of the delta pH results in a reduced rate of Ca2+ uptake. Also an artificially generated delta pH, interior acid, can drive Ca2+ uptake in S. cremoris membrane vesicles. Ca2+ uptake depends strongly on the presence of external phosphate while Ca2+-efflux-induced proton flux is independent of the presence of external phosphate. Ca2+ accumulation is abolished by the divalent cation ionophore A23187. Calcium extrusion from intact cells is accelerated by lactose. Collapse of the proton motive force by the uncoupler carbonylcyanide p-trifluoromethoxyphenylhydrazone or inhibition of the membrane-bound ATPase by N,N'-dicyclohexylcarbodiimide strongly inhibits Ca2+ release. Further studies on Ca2+ efflux at different external pH values in the presence of either valinomycin or nigericin suggested that Ca2+ exit from intact cells is an electrogenic process. It is concluded that Ca2+ efflux in S. cremoris is mediated by a secondary transport system catalyzing exchange of calcium ions and protons.

Bacteriorhodopsins↗
PubMed1986

Measurements of the proton motive force generated by cytochrome c oxidase from Bacillus subtilis in proteoliposomes and membrane vesicles.

Cytochrome c oxidase from Bacillus subtilis was reconstituted in liposomes and its energy-transducing properties were studied. The reconstitution procedure used included Ca2+-induced fusion of pre-formed membranes. The orientation of the enzyme in liposomes is influenced by the phospholipid composition of the membrane. Negatively charged phospholipids are essential for high oxidase activity and respiratory control. Analyses of the proteoliposomes by gel filtration, density gradient centrifugation and electron microscopy indicated a heterogeneity of the proteoliposomes with respect to size and respiratory control. Cytochrome c oxidase activity in the proteoliposomes resulted in the generation of a proton motive force, internally negative and alkaline. In the presence of the electron donor, ascorbate/N,N,N',N'-tetramethyl-p-phenylenediamine/cytochrome c or ascorbate/phenazine methosulphate, the reconstituted enzyme generated an electrical potential of 84 mV which was increased by the addition of nigericin to 95 mV and a pH gradient of 32 mV which was increased by the addition of valinomycin to 39 mV. Similar results were obtained with beef-heart cytochrome c oxidase reconstituted in liposomes. The maximal proton motive force which could be generated, assuming no endogenous ion leakage, varied over 110-140 mV. From this the efficiency of energy transduction by cytochrome c oxidase was calculated to be 18-23%, indicating that the oxidase is an efficient proton-motive-force-generating system.

Bacillus subtilis↗
PubMed1986

Functional incorporation of beef-heart cytochrome c oxidase into membranes of Streptococcus cremoris.

Beef heart mitochondrial cytochrome c oxidase has been incorporated into membrane vesicles derived from the homofermentative lactic acid bacterium Streptococcus cremoris. Proteoliposomes containing cytochrome c oxidase were fused with the bacterial membrane vesicles by means of a freeze/thaw sonication technique. Evidence that membrane fusion has taken place is presented by the demonstration that nonexchangeable fluorescent phospholipid probes, originally present only in the bacterial membrane or only in the liposomal membrane, are diluted in the membrane after fusion and, by sucrose gradient centrifugation, indicating a buoyant density of the membranes after fusion in between those of the starting membrane preparations. The fused membranes are endowed with a relatively low ion permeability which makes it possible to generate a high proton motive force (100 mV, inside negative and alkaline) by cytochrome-c-oxidase-mediated oxidation of the electron donor system ascorbate/N,N,N',N'-tetramethyl-p-phenylenediamine/cytochrome c. In the fused membranes this proton motive force can drive the uptake of several amino acids via secondary transport systems. The incorporation procedure described for primary proton pumps in biological membranes opens attractive possibilities for studies of proton-motive-force-dependent processes in isolated membrane vesicles from bacterial or eukaryotic origin which lack a suitable proton-motive-force-generating system.

Amino Acids↗
PubMed1985

Low pH-induced fusion of liposomes with membrane vesicles derived from Bacillus subtilis.

We have investigated the pH-dependent interaction between large unilamellar phospholipid vesicles (liposomes) and membrane vesicles derived from Bacillus subtilis, utilizing a fluorescent assay based on resonance energy transfer (RET) (Struck, D. K., Hoekstra, D., and Pagano, R. E. (1981) Biochemistry 20, 4093-4099). Efficient interaction occurs only with negatively charged liposomes, containing cardiolipin or phosphatidylserine, as revealed by the dilution of the RET probes from the liposomal bilayer into the bacterial membrane. The initial rate of fluorophore dilution increases steeply with decreasing pH. The interaction involves a process of membrane fusion, as indicated by the proportional transfer of cholesteryl-[1-14C]oleate, 14C-labeled egg PC, and the RET probes from the liposomes to the bacterial vesicles, the formation of interaction products with an intermediate buoyant density, and the appearance of colloidal gold, initially encapsulated in the liposomes, in the internal volume of fused structures as revealed by thin-section electron microscopy. Treatment of B. subtilis vesicles with trypsin strongly inhibits the fusion reaction, indicating the protein dependence of the process. Vesicles derived from Streptococcus cremoris or from the inner membrane of Escherichia coli also show low pH-dependent fusion with liposomes. The fusion process described in this paper may well be of considerable importance to studies on the mechanisms of membrane fusion and to studies on the structure and function of bacterial membranes. In addition, the fusion reaction could be utilized to deliver foreign substances into bacterial protoplasts.

Bacillus subtilis↗
PubMed1985

Incorporation of beef heart cytochrome c oxidase as a proton-motive force-generating mechanism in bacterial membrane vesicles.

Membrane vesicles derived from the strictly fermentative lactic acid bacterium Streptococcus cremoris have been fused with proteoliposomes containing the beef heart mitochondrial cytochrome c oxidase by means of a freeze/thaw-sonication technique. Evidence that fusion has taken place was obtained by freeze-etch electron microscopy, showing a less-dense intramembranous particle distribution in the fused membranes than in the bacterial membranes, and by sucrose gradient centrifugation, indicating a buoyant density of the majority of the membranes after fusion that was between the buoyant densities of the starting membrane preparations. In the fused membranes, 55-60% of the cytochrome c oxidase molecules are oriented with the cytochrome c binding site at the outer surface of the membrane. With the electron-donor system ascorbate/N,N,N',N'-tetramethyl-p-phenylenediamine/cytochrome c, a high proton-motive force (greater than 130 mV), inside negative and alkaline, can be generated in the fused membrane, and this proton-motive force can drive secondary transport of several amino acids. The procedure described can be used for incorporating a proton-motive force-generating system in isolated membrane vesicles from bacterial or eukaryotic origin that lack a suitable primary proton pump.

Animals↗
PubMedDate not supplied

Compartmentalization and transport in beta-lactam antibiotic biosynthesis by filamentous fungi.

A proper description of the biosynthesis of fungal beta-lactam antibiotics requires detailed knowledge of the cell biology of the producing organisms. This involves a delineation of the compartmentalization of the biosynthetic pathways, and of the consequential transport steps across the cell-boundary plasma membrane and across organellar membranes. Of the enzymes of the penicillin biosynthetic pathway in Penicillium chrysogenum and Aspergillus nidulans, delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine synthetase (ACVS) and isopenicillin N synthase (IPNS) probably have a cytosolic location. Acyl-coenzyme A:isopenicillin N acyltransferase (IAT) is located in microbodies. Of the two enzymes that may be involved in activation of the side chain, acetyl-coenzyme A synthetase (ACS) is located in the cytosol, and phenylacetyl-coenzyme A ligase (PCL) is probably located in the microbody. All enzymes of the cephalosporin biosynthesis pathway in Cephalosporium acremonium probably have a cytosolic location. The vacuole may play an ancillary role in the supply of precursor amino acids, and in the storage of intermediates. The distribution of precursors, intermediates, end- and side-products, the transport of nutrients. precursor, intermediates and products across the plasma membrane, and the transport of small solutes across organellar membranes, is discussed. The relevance of compartmentalization is considered against the background of recent biotechnological innovations of fungal beta-lactam biosynthesis pathways.

Anti-Bacterial Agents↗
PubMedDate not supplied

Bacteriocins: mechanism of membrane insertion and pore formation.

Lactic acid bacteria produce several types of pore forming peptides. Class I bacteriocins are lantibiotics that contain (methyl)lanthionine residues that may form intramolecular thioether rings. These peptides generally have a broad spectrum of activity and form unstable pores. Class II bacteriocins are small, heat stable peptides mostly with a narrow spectrum of activity. Most bacteriocins interact with anionic lipids that are abundantly present in the membranes of gram-positive bacteria. 'Docking molecules' may enhance the conductivity and stability of lantibiotic pores, while 'receptors' in the target membrane may determine specificity of class II bacteriocins. Insertion into the membrane of many bacteriocins is proton motive force driven. Lantibiotics may form pores according to a 'wedge-like' model, while class II bacteriocins may enhance membrane permeability either by the formation of a 'barrel stave' pore or by a 'carpet' mechanism.

Amino Acid Sequence↗