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PMID:8387496
| Citation |
Richarme, G, el Yaagoubi, A and Kohiyama, M (1993) The MglA component of the binding protein-dependent galactose transport system of Salmonella typhimurium is a galactose-stimulated ATPase. J. Biol. Chem. 268:9473-7 |
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| Abstract |
Binding protein-dependent transport systems mediate the accumulation of several ions, sugars, amino acids, and peptides in Gram-negative bacteria by using the energy of ATP hydrolysis and belong to a superfamily of membrane proteins which extends to eukaryotic cells and includes the multidrug resistance P-glycoprotein and the cystic fibrosis transmembrane conductance regulator. The binding protein-dependent galactose transport system of Salmonella typhimurium comprises four proteins which have been characterized previously by molecular cloning experiments (51,000-dalton MglA protein, with a stable proteolytic product of 38,000 daltons, 33,000-dalton MglB protein, 29,000-dalton MglC protein, 21,000-dalton MglE protein). By using a MglA hyperproducing strain, we have purified a galactose-stimulated ATPase which shows a single band in polyacrylamide gels under nondenaturing conditions and shows three bands at 51,000, 38,000, and 15,000 daltons on sodium dodecyl sulfate-polyacrylamide gels (our results suggest that the bands at 38,000 and 15,000 daltons represent proteolytic products of the 51,000-dalton protein). The ATPase activity coincides with the purified protein during the two last chromatographic steps of the purification procedure, and it cannot be isolated from a strain which does not contain the mglA gene. The MglA ATPase is stimulated 3-fold by galactose and hydrolyzes ATP to ADP and Pi (Km ATP = 60 microM, Ka galactose = 0.3 mM, Vmax = 140 nmol/min/mg of protein). The gamma-phosphate of ATP is transferred neither to galactose nor to the protein itself. Vanadate, N-ethylmaleimide and 5-methoxyindole-2-carboxylic acid, a specific inhibitor of binding protein-dependent transport systems, inhibit the MglA ATPase. |
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| Keywords |
Adenosine Triphosphatases/isolation & purification; Adenosine Triphosphatases/metabolism; Adenosine Triphosphate/metabolism; Bacterial Proteins/genetics; Bacterial Proteins/isolation & purification; Bacterial Proteins/metabolism; Chromatography; Chromatography, Affinity; Durapatite; Electrophoresis, Polyacrylamide Gel; Galactose/metabolism; Genes, Bacterial; Hydroxyapatites; Kinetics; Molecular Weight; Salmonella typhimurium/enzymology; Salmonella typhimurium/genetics |
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Significance
Annotations
| Gene product | Qualifier | GO Term | Evidence Code | with/from | Aspect | Extension | Notes | Status |
|---|---|---|---|---|---|---|---|---|
| GO:0016887: ATPase activity |
ECO:0000315: |
F |
Figure 3, showing that MglA had ATPase activity. MglA is specifically stimulated by galactose, while being uneffected by other compounds. Indication that the ATPase supports the implication of hydrolysis in protein-dependent transport system. Also figure 2 shows the peak of ATPase activity eluted from column that coincides with the peak of MglA protein. |
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