Structural basis for potassium transport in prokaryotes by KdpFABC
| Autor: | Casper Larsen, Michael Schlame, David L. Stokes, Marie E. Sweet, Bjørn Panyella Pedersen, Xihui Zhang |
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| Rok vydání: | 2021 |
| Předmět: |
0301 basic medicine
Models Molecular Protein subunit ATPase Membrane transport | P-type ATPase energy coupling | stress response 03 medical and health sciences 0302 clinical medicine ATP hydrolysis Operon Escherichia coli Cation Transport Proteins Adenosine Triphosphatases Multidisciplinary Binding Sites Ion Transport biology Chemistry Escherichia coli Proteins Membrane Proteins Transporter Membrane transport Biological Sciences 030104 developmental biology Membrane Cytoplasm P-type ATPase biology.protein Biophysics Potassium 030217 neurology & neurosurgery |
| Zdroj: | Proc Natl Acad Sci U S A Sweet, M E, Larsen, C, Zhang, X, Schlame, M, Pedersen, B P & Stokes, D L 2021, ' Structural basis for potassium transport in prokaryotes by KdpFABC ', Proceedings of the National Academy of Sciences of the United States of America, vol. 118, no. 29, e2105195118 . https://doi.org/10.1073/pnas.2105195118 |
| ISSN: | 1091-6490 |
| Popis: | KdpFABC is an oligomeric K+ transport complex in prokaryotes that maintains ionic homeostasis under stress conditions. The complex comprises a channel-like subunit (KdpA) from the superfamily of K+ transporters and a pump-like subunit (KdpB) from the superfamily of P-type ATPases. Recent structural work has defined the architecture and generated contradictory hypotheses for the transport mechanism. Here, we use substrate analogs to stabilize four key intermediates in the reaction cycle and determine the corresponding structures by cryogenic electron microscopy. We find that KdpB undergoes conformational changes consistent with other representatives from the P-type superfamily, whereas KdpA, KdpC, and KdpF remain static. We observe a series of spherical densities that we assign as K+ or water and which define a pathway for K+ transport. This pathway runs through an intramembrane tunnel in KdpA and delivers ions to sites in the membrane domain of KdpB. Our structures suggest a mechanism where ATP hydrolysis is coupled to K+ transfer between alternative sites in KdpB, ultimately reaching a low-affinity site where a water-filled pathway allows release of K+ to the cytoplasm. |
| Databáze: | OpenAIRE |
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