scholarly journals Coregulation of beta-galactoside uptake and hydrolysis by the hyperthermophilic bacterium Thermotoga neapolitana

1997 ◽  
Vol 63 (3) ◽  
pp. 969-972
Author(s):  
MY Galperin ◽  
KM Noll ◽  
AH Romano
Keyword(s):  
Active Transport ◽  
Transport System ◽  
Metabolic Energy ◽  
Free Sugar ◽  
Thermotoga Neapolitana ◽  
Inducer Exclusion ◽  
Hyperthermophilic Bacterium ◽  
Active Transport System ◽  
Hydrolysis Of ◽  
Beta Galactosidase

Regulation of the beta-galactoside transport system in response to growth substrates in the extremely thermophilic anaerobic bacterium Thermotoga neapolitana was studied with the nonmetabolizable analog methyl-beta-D-thiogalactopyranoside (TMG) as the transport substrate. T. neapolitana cells grown on galactose or lactose accumulated TMG against a concentration gradient in an intracellular free sugar pool that was exchangeable with external galactose or lactose and showed induced levels of beta-galactosidase. Cells grown on glucose, maltose, or galactose plus glucose showed no capacity to accumulate TMG, though these cells carried out active transport of the nonmetabolizable glucose analog 2-deoxy-D-glucose. Glucose neither inhibited TMG uptake nor caused efflux of preaccumulated TMG; rather, glucose promoted TMG uptake by supplying metabolic energy. These data show that beta-D-galactosides are taken up by T. neapolitana via an active transport system that can be induced by galactose or lactose and repressed by glucose but which is not inhibited by glucose. Thus, the phenomenon of catabolite repression is present in T. neapolitana with respect to systems catalyzing both the transport and hydrolysis of beta-D-galactosides, but inducer exclusion and inducer expulsion, mechanisms that regulate permease activity, are not present. Regulation is manifest at the level of synthesis of the beta-galactoside transport system but not in the activity of the system.

scholarly journals The glucose transport system of the hyperthermophilic anaerobic bacterium Thermotoga neapolitana

1996 ◽  
Vol 62 (8) ◽  
pp. 2915-2918
Author(s):  
MY Galperin ◽  
KM Noll ◽  
AH Romano
Keyword(s):  
Glucose Transport ◽  
Transport System ◽  
Anaerobic Bacterium ◽  
External Source ◽  
Free Sugar ◽  
Thermotoga Neapolitana ◽  
Phosphotransferase System ◽  
Cell Extracts ◽  
Glucose Transport System ◽  
Active Transport System

The glucose transport system of the extremely thermophilic anaerobic bacterium Thermotoga neapolitana was studied with the nonmetabolizable glucose analog 2-deoxy-D-glucose (2-DOG). T. neapolitana accumulated 2-DOG against a concentration gradient in an intracellular free sugar pool that was exchangeable with external source of energy, such as pyruvate, and was inhibited by arsenate and gramicidin D. There was no phosphoenolpyruvate-dependent phosphorylation of glucose, 2-DOG, or fructose by cell extracts or toluene-treated cells, indicating the absence of a phosphoenolpyruvate:sugar phosphotransferase system. These data indicate that D-glucose is taken up by T. neapolitana via an active transport system that is energized by an ion gradient generated by ATP, derived from substrate-level phosphorylation.

On the structural organization of biological pumps and channels

1984 ◽  
Vol 42 ◽  
pp. 138-141
Author(s):  
G. Zampighi ◽  
M. Kreman
Keyword(s):  
Active Transport ◽  
Transport System ◽  
Plasma Membranes ◽  
Transport Proteins ◽  
Molecular Organization ◽  
Passive Transport ◽  
Concentration Gradients ◽  
Cell Functions ◽  
Natural Concentration ◽  
Active Transport System

The plasma membranes of most animal cells contain transport proteins which function to provide passageways for the transported species across essentially impermeable lipid bilayers. The channel is a passive transport system which allows the movement of ions and low molecular weight molecules along their concentration gradients. The pump is an active transport system and can translocate cations against their natural concentration gradients. The actions and interplay of these two kinds of transport proteins control crucial cell functions such as active transport, excitability and cell communication. In this paper, we will describe and compare several features of the molecular organization of pumps and channels. As an example of an active transport system, we will discuss the structure of the sodium and potassium ion-activated triphosphatase [(Na+ +K+)-ATPase] and as an example of a passive transport system, the communicating channel of gap junctions and lens junctions.

scholarly journals Actions of external hypertonic urea, ADH, and theophylline on transcellular and extracellular solute permeabilities in frog skin.

1975 ◽  
Vol 65 (5) ◽  
pp. 599-615 ◽  
Author(s):  
L J Mandel
Keyword(s):  
Linear Relationship ◽  
Active Transport ◽  
Transport System ◽  
Frog Skin ◽  
Open Circuit Potential ◽  
Open Circuit ◽  
Solute Permeability ◽  
Parallel Lines ◽  
Paracellular Pathways ◽  
Active Transport System

Increases in transepithelial solute permeability were elicited in the frog skin with external hypertonic urea, theophylline, and vasopressin (ADH). In external hypertonic urea, which is known to increase the permeability of the extracellular (paracellular) pathway, the unidirectional transepithelial fluxes of Na (passive), K, Cl, and urea increased substantially while preserving a linear relationship to each other. The same linear relationship was also observed for the passive Na and urea fluxes in regular Ringer and under stimulation with ADH or 10 mM theophylline, indicating that their permeation pathway was extracellular. A linear relationship between Cl and urea fluxes could be demonstrated if the skins were separated according to their open circuit potentials; parallel lines were obtained with increasing intercepts on the Cl axis as the open circuit potential decreased. The slopes of the Cl vs. urea lines were not different from that obtained in external hypertonic urea, indicating that this relationship described the extracellular movement of Cl. The intercept on the ordinate was interpreted as the contribution from the transcellular Cl movement. In the presence of 0.5 mM theophylline or 10 mU/ml of ADH, mainly the transcellular movement of Cl increased, whereas 10 mM theophylline caused increases in both transcellular and extracellular Cl fluxes. These and other data were interpreted in terms of a possible intracellular control of the theophylline-induced increase in extracellular fluxes. The changes in passive solute permeability were shown to be independent of active transport. The responses of the active transport system, the transcellular and paracellular pathways to theophylline and ADH could be explained in terms of the different resulting concentrations of cyclic 3'-5'-AMP produced by each of these substances in the tissue.

A linked active transport system for Na+ and K+ in a glial cell line

1976 ◽  
Vol 104 (1) ◽  
pp. 93-105 ◽  
Author(s):  
Gary Kukes ◽  
Jean De Vellis ◽  
Rafael Elul
Keyword(s):  
Cell Line ◽  
Glial Cell ◽  
Active Transport ◽  
Transport System ◽  
Active Transport System

The pH-dependent uptake of putrescine by Pseudomonas acidovorans and its incorporation into bacteriophage DNA

1983 ◽  
Vol 29 (7) ◽  
pp. 827-829 ◽  
Author(s):  
D. L. Bruce ◽  
R. A. J. Warren
Keyword(s):  
Active Transport ◽  
Transport System ◽  
Normal Condition ◽  
Intracellular Pool ◽  
Pseudomonas Acidovorans ◽  
Ph Dependent ◽  
Active Transport System

Lack of an active transport system prevents Pseudomonas acidovorans taking up putrescine under normal condition of growth. At pH 9.5, however, putrescine does enter the cell. That putrescine enters the intracellular pool is shown by its conversion to 2-hydroxyputrescine and spermidine after the cells are returned to pH 7.0. The accumulated putrescine can be used to label specifically the α-putrescinylthymine residues of bacteriophage [Formula: see text] DNA.

Participation of an active transport system in berberine-secreting cultured cells of Thalictrum minus

1987 ◽  
Vol 6 (5) ◽  
pp. 356-359 ◽  
Author(s):  
H. Yamamoto ◽  
M. Suzuki ◽  
Y. Suga ◽  
H. Fukui ◽  
M. Tabata
Keyword(s):  
Active Transport ◽  
Transport System ◽  
Cultured Cells ◽  
Thalictrum Minus ◽  
Active Transport System

Reconstitution of an ATP-mediated Active Transport System across Black Lipid Membranes

Nature ◽  
1969 ◽  
Vol 222 (5196) ◽  
pp. 871-872 ◽  
Author(s):  
MAHENDRA K. JAIN ◽  
ALFRED STRICKHOLM ◽  
E. H. CORDES
Keyword(s):  
Active Transport ◽  
Transport System ◽  
Lipid Membranes ◽  
Black Lipid Membranes ◽  
Active Transport System
Sign in / Sign up

Export Citation Format

Share Document