Abstract
P-type ATPases ubiquitously pump cations across biological membranes to maintain vital ion gradients. Among those, the chimeric K+ uptake system KdpFABC is unique. While ATP hydrolysis is accomplished by the P-type ATPase subunit KdpB, K+ has been assumed to be transported by the channel-like subunit KdpA. A first crystal structure uncovered its overall topology, suggesting such a spatial separation of energizing and transporting units. Here, we report two cryo-EM structures of the 157 kDa, asymmetric KdpFABC complex at 3.7 Å and 4.0 Å resolution in an E1 and an E2 state, respectively. Unexpectedly, the structures suggest a translocation pathway through two half-channels along KdpA and KdpB, uniting the alternating-access mechanism of actively pumping P-type ATPases with the high affinity and selectivity of K+ channels. This way, KdpFABC would function as a true chimeric complex, synergizing the best features of otherwise separately evolved transport mechanisms.
Original language | English |
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Article number | 4971 |
Number of pages | 10 |
Journal | Nature Communications |
Volume | 9 |
Issue number | 1 |
DOIs | |
Publication status | Published - 26-Nov-2018 |
Keywords
- P-TYPE ATPASE
- AMINO-ACID SUBSTITUTIONS
- MEMBRANE REGION M-2C2
- UPTAKE SYSTEM KTRAB
- ESCHERICHIA-COLI
- KDP-ATPASE
- PHOSPHORYLATION SITE
- CATION-TRANSPORT
- ASPARTIC-ACID
- HIGH-AFFINITY
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