6HRB

Cryo-EM structure of the KdpFABC complex in an E2 inward-facing state (state 2)

Summary for 6HRB

• Entry DOI: 10.2210/pdb6hrb/pdb
• Related: 6HRA
• EMDB information: 0257 0258
• Descriptor: Potassium-transporting ATPase potassium-binding subunit, Potassium-transporting ATPase ATP-binding subunit, Potassium-transporting ATPase KdpC subunit, ... (5 entities in total)
• Functional Keywords: p-type atpase superfamily of k+ transporters (skt) potassium uptake system four subunit complex, membrane protein
• Biological source: Escherichia coli (strain K12); More
• Total number of polymer chains: 4
• Total formula weight: 154958.30

Authors

Stock, C.,Hielkema, L.,Tascon, I.,Wunnicke, D.,Oostergetel, G.T.,Azkargorta, M.,Paulino, C.,Haenelt, I. (deposition date: 2018-09-26, release date: 2018-12-05, Last modification date: 2024-11-13)

Primary citation

Stock, C.,Hielkema, L.,Tascon, I.,Wunnicke, D.,Oostergetel, G.T.,Azkargorta, M.,Paulino, C.,Hanelt, I.
Cryo-EM structures of KdpFABC suggest a K+transport mechanism via two inter-subunit half-channels.
Nat Commun, 9:4971-4971, 2018

PubMed 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.

PubMed: 30478378
DOI: 10.1038/s41467-018-07319-2

Experimental method

ELECTRON MICROSCOPY (4 Å)