6hra | pdb_00006hra
Cryo-EM structure of the KdpFABC complex in an E1 outward-facing state (state 1)
Structural highlights
FunctionKDPA_ECOLI Part of the high-affinity ATP-driven potassium transport (or Kdp) system, which catalyzes the hydrolysis of ATP coupled with the electrogenic transport of potassium into the cytoplasm (PubMed:2849541, PubMed:8499455, PubMed:23930894). This subunit binds and transports the potassium across the cytoplasmic membrane (PubMed:7896809).[1] [2] [3] [4] Publication Abstract from PubMedP-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 A and 4.0 A 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. Cryo-EM structures of KdpFABC suggest a K(+) transport mechanism via two inter-subunit half-channels.,Stock C, Hielkema L, Tascon I, Wunnicke D, Oostergetel GT, Azkargorta M, Paulino C, Hanelt I Nat Commun. 2018 Nov 26;9(1):4971. doi: 10.1038/s41467-018-07319-2. PMID:30478378[5] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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