6v4j
From Proteopedia
Structure of TrkH-TrkA in complex with ATP
Structural highlights
Function[TRKH_VIBPA] Low-affinity potassium transport system. Interacts with trk system potassium uptake protein TrkA and requires TrkE for transport activity. Selective for permeation of potassium ion and rubidium ion over smaller ions such as natrium or litium. Publication Abstract from PubMedTrkH is a bacterial ion channel implicated in K(+) uptake and pH regulation. TrkH assembles with its regulatory protein, TrkA, which closes the channel when bound to ADP and opens it when bound to ATP. However, it is unknown how nucleotides control the gating of TrkH through TrkA. Here we report the structures of the TrkH-TrkA complex in the presence of ADP or ATP. TrkA forms a tetrameric ring when bound to ADP and constrains TrkH to a closed conformation. The TrkA ring splits into two TrkA dimers in the presence of ATP and releases the constraints on TrkH, resulting in an open channel conformation. Functional studies show that both the tetramer-to-dimer conversion of TrkA and the loss of constraints on TrkH are required for channel gating. In addition, deletion of TrkA in Escherichia coli depolarizes the cell, suggesting that the TrkH-TrkA complex couples changes in intracellular nucleotides to membrane potential. TrkA undergoes a tetramer-to-dimer conversion to open TrkH which enables changes in membrane potential.,Zhang H, Pan Y, Hu L, Hudson MA, Hofstetter KS, Xu Z, Rong M, Wang Z, Prasad BVV, Lockless SW, Chiu W, Zhou M Nat Commun. 2020 Jan 28;11(1):547. doi: 10.1038/s41467-019-14240-9. PMID:31992706[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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