Small Substrate Transport and Mechanism of a Molybdate ATP Binding Cassette Transporter in a Lipid Environment
| Autor: | Amy L. Davidson, Alistair Harrison, Austin J. Rice, Frances Joan D. Alvarez, Heather W. Pinkett |
|---|---|
| Rok vydání: | 2014 |
| Předmět: |
Lipid Bilayers
ATP-binding cassette transporter Molybdate Biology Biochemistry Cell membrane 03 medical and health sciences chemistry.chemical_compound Adenosine Triphosphate Bacterial Proteins medicine Lipid bilayer Molecular Biology Ion transporter Nutrient Uptake 030304 developmental biology Molybdenum 0303 health sciences Ion Transport Reverse Transcriptase Polymerase Chain Reaction 030306 microbiology Membrane transport protein Hydrolysis Electron Paramagnetic Resonance (EPR) Cell Membrane Electron Spin Resonance Spectroscopy Membrane Transport Proteins Biological membrane Gene Expression Regulation Bacterial Cell Biology Membrane transport Lipids Haemophilus influenzae ABC Transporter ATP medicine.anatomical_structure Membrane Transport chemistry Liposomes Mutation Periplasm biology.protein ATP-Binding Cassette Transporters Molecular Biophysics |
| Zdroj: | The Journal of Biological Chemistry |
| ISSN: | 0021-9258 |
| DOI: | 10.1074/jbc.m114.563783 |
| Popis: | Background: Multiple ABC transporters work in concert to transport the same substrate. Results: MolBC-A allows for additional Mo uptake in periods of high external molybdate concentration. Conclusion: Utilizing the established transport mechanism, molybdate uptake is concentration-dependent. Significance: Our studies address the impact the lipid environment has on the mechanism of MolBC-A as well as the role this transporter plays in molybdate uptake. Embedded in the plasma membrane of all bacteria, ATP binding cassette (ABC) importers facilitate the uptake of several vital nutrients and cofactors. The ABC transporter, MolBC-A, imports molybdate by passing substrate from the binding protein MolA to a membrane-spanning translocation pathway of MolB. To understand the mechanism of transport in the biological membrane as a whole, the effects of the lipid bilayer on transport needed to be addressed. Continuous wave-electron paramagnetic resonance and in vivo molybdate uptake studies were used to test the impact of the lipid environment on the mechanism and function of MolBC-A. Working with the bacterium Haemophilus influenzae, we found that MolBC-A functions as a low affinity molybdate transporter in its native environment. In periods of high extracellular molybdate concentration, H. influenzae makes use of parallel molybdate transport systems (MolBC-A and ModBC-A) to take up a greater amount of molybdate than a strain with ModBC-A alone. In addition, the movement of the translocation pathway in response to nucleotide binding and hydrolysis in a lipid environment is conserved when compared with in-detergent analysis. However, electron paramagnetic resonance spectroscopy indicates that a lipid environment restricts the flexibility of the MolBC translocation pathway. By combining continuous wave-electron paramagnetic resonance spectroscopy and substrate uptake studies, we reveal details of molybdate transport and the logistics of uptake systems that employ multiple transporters for the same substrate, offering insight into the mechanisms of nutrient uptake in bacteria. |
| Databáze: | OpenAIRE |
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