Cryo-EM structures of KdpFABC suggest a K+ transport mechanism via two inter-subunit half-channels

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 ATPas
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.
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Metadaten
Author:Charlott Stock, Lisa Hielkema, Igor Tascón, Dorith Wunnicke, Gerrit Tjamme Oostergetel, Mikel Azkargorta, Cristina Paulino, Inga Hänelt
URN:urn:nbn:de:hebis:30:3-478735
DOI:http://dx.doi.org/10.1038/s41467-018-07319-2
ISSN:2041-1723
Pubmed Id:http://www.ncbi.nlm.nih.gov/pubmed?term=30478378
Parent Title (English):Nature Communications
Publisher:Nature Publishing Group UK
Place of publication:[London]
Document Type:Article
Language:English
Year of Completion:2018
Date of first Publication:2018/11/26
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Release Date:2018/12/06
Tag:Cryoelectron microscopy; Ion transport; Permeation and transport; Potassium channels
Volume:9
Issue:1, Art. 4971
Pagenumber:10
First Page:1
Last Page:10
Note:
Rights and permissions: Open Access: This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.
Institutes:Biochemie und Chemie
Dewey Decimal Classification:540 Chemie und zugeordnete Wissenschaften
Sammlungen:Universitätspublikationen
Licence (German):License LogoCreative Commons - Namensnennung 4.0

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