8XMI

Potassium transporter KtrAB from Bacillus subtilis in ATP-bound state with addition of EDTA and EGTA, C1 symmetry

Summary for 8XMI

• Entry DOI: 10.2210/pdb8xmi/pdb
• EMDB information: 38478
• Descriptor: Ktr system potassium uptake protein A, Ktr system potassium uptake protein B, ADENOSINE-5'-TRIPHOSPHATE, ... (5 entities in total)
• Functional Keywords: ktrab, rck, potassium, transporter, transport protein
• Biological source: Bacillus subtilis; More
• Total number of polymer chains: 12
• Total formula weight: 397526.04

Authors

Chang, Y.K.,Chiang, W.T.,Hu, N.J.,Tsai, M.D. (deposition date: 2023-12-27, release date: 2024-04-03, Last modification date: 2024-05-22)

Primary citation

Chiang, W.T.,Chang, Y.K.,Hui, W.H.,Chang, S.W.,Liao, C.Y.,Chang, Y.C.,Chen, C.J.,Wang, W.C.,Lai, C.C.,Wang, C.H.,Luo, S.Y.,Huang, Y.P.,Chou, S.H.,Horng, T.L.,Hou, M.H.,Muench, S.P.,Chen, R.S.,Tsai, M.D.,Hu, N.J.
Structural basis and synergism of ATP and Na + activation in bacterial K + uptake system KtrAB.
Nat Commun, 15:3850-3850, 2024

PubMed Abstract: The K uptake system KtrAB is essential for bacterial survival in low K environments. The activity of KtrAB is regulated by nucleotides and Na. Previous studies proposed a putative gating mechanism of KtrB regulated by KtrA upon binding to ATP or ADP. However, how Na activates KtrAB and the Na binding site remain unknown. Here we present the cryo-EM structures of ATP- and ADP-bound KtrAB from Bacillus subtilis (BsKtrAB) both solved at 2.8 Å. A cryo-EM density at the intra-dimer interface of ATP-KtrA was identified as Na, as supported by X-ray crystallography and ICP-MS. Thermostability assays and functional studies demonstrated that Na binding stabilizes the ATP-bound BsKtrAB complex and enhances its K flux activity. Comparing ATP- and ADP-BsKtrAB structures suggests that BsKtrB Arg417 and Phe91 serve as a channel gate. The synergism of ATP and Na in activating BsKtrAB is likely applicable to Na-activated K channels in central nervous system.

PubMed: 38719864
DOI: 10.1038/s41467-024-48057-y

Experimental method

ELECTRON MICROSCOPY (3 Å)