Cryo-EM structures of KdpFABC suggest a K transport mechanism via two inter-subunit half-channelsStock, C., Hielkema, L., Tascón, I., Wunnicke, D., Oostergetel, G. T., Azkargorta, M., Paulino, C. & Hänelt, I., 26-Nov-2018, In : Nature Communications. 9, 1, 10 p., 4971.
Research output: Contribution to journal › Article › Academic › peer-review
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.
|Number of pages||10|
|Publication status||Published - 26-Nov-2018|
- 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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