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Literature summary for 7.5.2.6 extracted from
- Functional role of transmembrane helix 6 in drug binding and transport by the ABC transporter MsbA (2008), Biochemistry, 47, 10904-10914.
Activating Compound
| Activating Compound | Comment | Organism | Structure |
|---|---|---|---|
| taxol | 1.4fold stimulation of the wild-type enzyme, no stimulation of mutant S289A/S290A. Erythromycin resistance is conferred by wild-type or mutant MsbA, taxol is sufficient to reverse the erythromycin resistance of wild-type MsbA-expressing cells | Escherichia coli |  |
Cloned(Commentary)
| Cloned (Comment) | Organism |
|---|---|
| gene msbA, DNA and amino acid sequence determination and analysis of wild-type and mutant enzymes, expression of His6-tagged proteins in Lactococcus lactis strain NZ9000 DELTAlmrA DELTAlmrCD | Escherichia coli |
Crystallization (Commentary)
| Crystallization (Comment) | Organism |
|---|---|
| X-ray diffraction structure determination and analysis at 3.7 A resolution and analysis of structure PDB ID 3b60 | Salmonella enterica subsp. enterica serovar Typhimurium |
Protein Variants
| Protein Variants | Comment | Organism |
|---|---|---|
| additional information | change-in-speci?city mutations colocalize in a major groove in each of the two wings of transmembrane helices, that point away from one another to ward the periplasm. Near the apex of the groove,the periplasmic side of transmembrane helice 6, TMH6, in both monomers contains a hot spot of change-in-speci?city mutations and residues which, when replaced with cysteines in ABCB1, covalently interact with thiol-reactive drug analogues | Salmonella enterica subsp. enterica serovar Typhimurium |
| additional information | construction of point and deletion muitants, e.g. DELTAK382, change-in-specificity mutations colocalize in a major groove in each of the two wings of transmembrane helices, that point away from one another to ward the periplasm. Near the apex of the groove, the periplasmic side of transmembrane helice 6, TMH6, in both monomers contains a hot spot of change-in-specificity mutations and residues which, when replaced with cysteines in ABCB1, covalently interact with thiol-reactive drug analogues, drug-protein interaction analysis, overview | Escherichia coli |
| S289A/S290A | site-directed mutagenesis, the mutant enzyme is not stimulated by taxol in contrast to the wild-type enzyme. The mutation does not alter the interaction of MsbA with Hoechst33342 but reduces the level of inhibition of MsbA-mediated Hoechst33342 transport by taxol. The mutant MsbA is affected in the binding and transport of ethidium | Escherichia coli |
Inhibitors
| Inhibitors | Comment | Organism | Structure |
|---|---|---|---|
| ethidium | antimitotic drug, vinblastine, directly competes with ethidium for binding to MsbA | Escherichia coli | |
| Hoechst 33342 | complete inhibition of MsbA-mediated Hoechst33342 transport by 0.025 mM taxol, noncompetitive kinetics with Ki of 0.0066 mM, overview | Escherichia coli | |
| vinblastine | antimitotic drug, vinblastine, directly competes with ethidium for binding to MsbA | Escherichia coli | |
Localization
| Localization | Comment | Organism | GeneOntology No. | Textmining |
|---|---|---|---|---|
| membrane | orientation to the periplasmic side | Escherichia coli | 16020 | - |
| membrane | orientation to the periplasmic side | Salmonella enterica subsp. enterica serovar Typhimurium | 16020 | - |
Natural Substrates/ Products (Substrates)
| Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| ATP + H2O + lipopolysaccharide/in | Escherichia coli | - |
ADP + phosphate + lipopolysaccharide/out | - |
? | |
| ATP + H2O + lipopolysaccharide/in | Salmonella enterica subsp. enterica serovar Typhimurium | - |
ADP + phosphate + lipopolysaccharide/out | - |
? | |
| additional information | Escherichia coli | MsbA is an essential ABC transporter in Gram-negative bacteria | ? | - |
? | |
| additional information | Salmonella enterica subsp. enterica serovar Typhimurium | MsbA is an essential ABC transporter in Gram-negative bacteria | ? | - |
? | |
Organism
| Organism | UniProt | Comment | Textmining |
|---|---|---|---|
| Escherichia coli | - |
gene msbA | - |
| Salmonella enterica subsp. enterica serovar Typhimurium | P63359 | gene msbA | - |
Purification (Commentary)
| Purification (Comment) | Organism |
|---|---|
| recombinant His6-tagged wild-type and mutant enzymes from Lactobacillus lactis by soluibilization from membranes with detergent n-dodecyl beta-D-maltoside, and nickel affinity chromatography, formation of inside-out membrane vesicles | Escherichia coli |
Specific Activity [micromol/min/mg]
| Specific Activity Minimum [µmol/min/mg] | Specific Activity Maximum [µmol/min/mg] | Comment | Organism |
|---|---|---|---|
| 0.624 | - |
unstimulated recombinant His6-tagged wild-type enzyme activity | Escherichia coli |
| 0.726 | - |
recombinant His6-tagged mutant S289A/S290A in presence or absence of taxol | Escherichia coli |
| 0.835 | - |
taxol stimulated recombinant His6-tagged wild-type enzyme activity | Escherichia coli |
Substrates and Products (Substrate)
| Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| ATP + H2O + lipopolysaccharide/in | - |
Escherichia coli | ADP + phosphate + lipopolysaccharide/out | - |
? | |
| ATP + H2O + lipopolysaccharide/in | - |
Salmonella enterica subsp. enterica serovar Typhimurium | ADP + phosphate + lipopolysaccharide/out | - |
? | |
| additional information | MsbA is an essential ABC transporter in Gram-negative bacteria | Escherichia coli | ? | - |
? | |
| additional information | MsbA is an essential ABC transporter in Gram-negative bacteria | Salmonella enterica subsp. enterica serovar Typhimurium | ? | - |
? | |
Subunits
| Subunits | Comment | Organism |
|---|---|---|
| homodimer | structure modelling | Escherichia coli |
| homodimer | structure modelling | Salmonella enterica subsp. enterica serovar Typhimurium |
Synonyms
| Synonyms | Comment | Organism |
|---|---|---|
| MsbA | - |
Escherichia coli |
| MsbA | - |
Salmonella enterica subsp. enterica serovar Typhimurium |
Temperature Optimum [°C]
| Temperature Optimum [°C] | Temperature Optimum Maximum [°C] | Comment | Organism |
|---|---|---|---|
| 30 | - |
assay at | Escherichia coli |
pH Optimum
| pH Optimum Minimum | pH Optimum Maximum | Comment | Organism |
|---|---|---|---|
| 8 | - |
assay at | Escherichia coli |
Cofactor
| Cofactor | Comment | Organism | Structure |
|---|---|---|---|
| ATP | - |
Escherichia coli | |
| ATP | - |
Salmonella enterica subsp. enterica serovar Typhimurium | |
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