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Structure paper

タイトル	Cryo-EM structures of KdpFABC suggest a K transport mechanism via two inter-subunit half-channels.
ジャーナル・号・ページ	Nat Commun, Vol. 9, Issue 1, Page 4971, Year 2018
掲載日	2018年11月26日
著者	C Stock / L Hielkema / I Tascón / D Wunnicke / G T Oostergetel / M Azkargorta / C Paulino / I Hänelt /
PubMed 要旨	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 ...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.
リンク	Nat Commun / PubMed:30478378 / PubMed Central
手法	EM (単粒子)
解像度	3.7 - 4.0 Å
構造データ	0257 6hra EMDB-0257, PDB-6hra: Cryo-EM structure of the KdpFABC complex in an E1 outward-facing state (state 1) 手法: EM (単粒子) / 解像度: 3.7 Å 0258 6hrb EMDB-0258, PDB-6hrb: Cryo-EM structure of the KdpFABC complex in an E2 inward-facing state (state 2) 手法: EM (単粒子) / 解像度: 4.0 Å
化合物	ChemComp-K: Unknown entry / カリウムカチオン
由来	Escherichia coli K-12 (大腸菌) escherichia coli (strain k12) (大腸菌)
キーワード	MEMBRANE PROTEIN (膜タンパク質) / P-type ATPase superfamily of K+ transporters (SKT) potassium uptake system four subunit complex