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Literature summary for 7.5.2.6 extracted from
- ATPase activity of the MsbA lipid flippase of Escherichia coli (2002), J. Biol. Chem., 277, 36697-36705 .
Activating Compound
| Activating Compound | Comment | Organism | Structure |
|---|---|---|---|
| 3-deoxy-D-mannooctulosonic acid (Kdo)2-lipid A | increases the ATPase activity 4-5fold, with half-maximal stimulation at 0.021 mM Kdo2-lipid A, addition of Kdo2-lipid A increases the Vmax and decreases the Km. The stimulation is only seen with hexaacylated lipid A species and not with precursors, such as diacylated lipid X or tetraacylated lipid IVA | Escherichia coli | |
| hexaacylated lipid A | is an especially potent activator | Escherichia coli | |
| Phospholipids | stimulate the ATPase activity of the purified enzyme | Escherichia coli |  |
Cloned(Commentary)
| Cloned (Comment) | Organism |
|---|---|
| gene msbA, recombinant overexpression of His6-tagged wild-type and mutant enzymes in Escherichia coli | Escherichia coli |
Protein Variants
| Protein Variants | Comment | Organism |
|---|---|---|
| A270T | site-directed mutagenesis, temperature-sensitive MsbA allele, the mutation renders cells temperature-sensitive for growth and lipid export, the mutant displays ATPase activity similar to that of the wild-type protein at 30°C but is significantly reduced at 42°C | Escherichia coli |
Inhibitors
| Inhibitors | Comment | Organism | Structure |
|---|---|---|---|
| vanadate | inhibitory effect of vanadate on the ATPase activity of MsbA | Escherichia coli | |
KM Value [mM]
| KM Value [mM] | KM Value Maximum [mM] | Substrate | Comment | Organism | Structure |
|---|---|---|---|---|---|
| 0.379 | - |
ATP | reconstituted purified recombinant His-tagged enzyme in liposomes prepared from Escherichia coli phospholipids, pH 7.5, 37°C, ATP hydrolysis in presence of 10 mM Mg2+ and 0.021 mM Kdo2-lipid A | Escherichia coli | |
| 0.878 | - |
ATP | reconstituted purified recombinant His-tagged enzyme in liposomes prepared from Escherichia coli phospholipids, pH 7.5, 37°C, ATP hydrolysis in presence of 10 mM Mg2+ | Escherichia coli | |
Localization
| Localization | Comment | Organism | GeneOntology No. | Textmining |
|---|---|---|---|---|
| inner membrane | - |
Escherichia coli | - |
- |
Metals/Ions
| Metals/Ions | Comment | Organism | Structure |
|---|---|---|---|
| Mg2+ | required | Escherichia coli | |
Natural Substrates/ Products (Substrates)
| Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| ATP + H2O + lipid A-core oligosaccharide[side 1] | Escherichia coli | - |
ADP + phosphate + lipid A-core oligosaccharide[side 2] | - |
? | |
| ATP + H2O + lipid A-core oligosaccharide[side 1] | Escherichia coli K12 | - |
ADP + phosphate + lipid A-core oligosaccharide[side 2] | - |
? | |
Organism
| Organism | UniProt | Comment | Textmining |
|---|---|---|---|
| Escherichia coli | P60752 | - |
- |
| Escherichia coli K12 | P60752 | - |
- |
Purification (Commentary)
| Purification (Comment) | Organism |
|---|---|
| recombinant His6-tagged wild-type and mutant enzymes from Escherichia coli by ultraccentrifugation, detergent solubilization, again ultraccentrifugation, and nickel affinity chromatography, to over 95% purity | Escherichia coli |
Renatured (Commentary)
| Renatured (Comment) | Organism |
|---|---|
| the enzyme is reconstituted into liposomes prepared from Escherichia coli phospholipids | Escherichia coli |
Substrates and Products (Substrate)
| Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| ATP + H2O + lipid A-core oligosaccharide[side 1] | - |
Escherichia coli | ADP + phosphate + lipid A-core oligosaccharide[side 2] | - |
? | |
| ATP + H2O + lipid A-core oligosaccharide[side 1] | - |
Escherichia coli K12 | ADP + phosphate + lipid A-core oligosaccharide[side 2] | - |
? | |
Subunits
| Subunits | Comment | Organism |
|---|---|---|
| homodimer | structure at 4.5 A resolution | Escherichia coli |
Synonyms
| Synonyms | Comment | Organism |
|---|---|---|
| lipid flippase | - |
Escherichia coli |
| MsbA | - |
Escherichia coli |
Temperature Optimum [°C]
| Temperature Optimum [°C] | Temperature Optimum Maximum [°C] | Comment | Organism |
|---|---|---|---|
| 37 | - |
assay at | Escherichia coli |
pH Optimum
| pH Optimum Minimum | pH Optimum Maximum | Comment | Organism |
|---|---|---|---|
| 7.5 | - |
assay at | Escherichia coli |
Cofactor
| Cofactor | Comment | Organism | Structure |
|---|---|---|---|
| ATP | - |
Escherichia coli | |
General Information
| General Information | Comment | Organism |
|---|---|---|
| malfunction | depletion or loss of function of MsbA results in the accumulation of lipopolysaccharide and phospholipids in the inner membrane of Escherichia coli | Escherichia coli |
| physiological function | Escherichia coli MsbA is a lipid-activated ATPase with a proposed role in phospholipid export | Escherichia coli |
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