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3.A.3.7.1
K+-ATPase (uptake), KdpFABC. (KdpA is homologous to other K+ transporters such as KcsA (1.A.1.1.1), KtrB (2.A.38.4.2 and 2.A.38.4.3), and HKT (2.A.38.3.1 and 2.A.38.3.2); KdpB is homologous to P-ATPase α-subunits; KdpC and KdpF may facilitate complex assembly and stabilize the complex (Bramkamp et al., 2007; Haupt et al., 2005; Greie and Altendorf, 2007; Irzik et al., 2011). The KdpFABC acts as a functional and structural dimer with the two KdpB subunits in direct contact, but the enzyme can dissociate to the monomer (Heitkamp et al., 2008). KdpF is part of and stabilizes the KdpABC complex (Gassel et al., 1999).  Transcription of the kdp operon is activated by the KdpDE sensor kinase/response regulator pair, and unphosphorylated IIANtr of the PTS (TC# 4.A) binds KdpD to stimulate its activity, thereby enhancing kdp operon expression (Lüttmann et al. 2009, Lüttmann et al. 2015). Transcriptional regulation of the Pseudomonas putida kdpFABC operon by the KdpDE sensor kinase/response regulator by direct interaction of IIANtr of the PTS with KdpD has also been studied (Wolf et al. 2015). The 2.9 Å X-ray structure of the complete Escherichia coli KdpFABC complex with a potassium ion within the selectivity filter of KdpA and a water molecule at a canonical cation site in the transmembrane domain of KdpB has been solved (Huang et al. 2017). The structure reveals two structural elements that appear to mediate the coupling between these two subunits: a protein-embedded tunnel runs between these potassium and water sites, and a helix controlling the cytoplasmic gate of KdpA is linked to the phosphorylation domain of KdpB. A mechanism that repurposes protein channel architecture for active transport across biomembranes was proposed (Huang et al. 2017). The cytoplasmic C-terminal domain of KdpD functions as a K+ sensor (Rothenbücher et al. 2006). Serine phosphorylated KdpB is trapped in a conformation where the ion-binding site is hydrated via an intracellular pathway between TMSs M1 and M2 which opens in response to the rearrangement of cytoplasmic domains, resulting from phosphorylation (Dubey et al. 2021). This causes pump inhibition in the presence of high K+ resulting in ATP conservation.

Accession Number:P03959
Protein Name:ATKA aka KDPA aka B0698
Length:557
Molecular Weight:59189.00
Species:Escherichia coli [83333]
Number of TMSs:12
Location1 / Topology2 / Orientation3: Cell inner membrane1 / Multi-pass membrane protein2
Substrate K+

Cross database links:

RefSeq: AP_001336.1    NP_415226.1   
Entrez Gene ID: 946045   
Pfam: PF03814   
BioCyc: EcoCyc:EG10513-MONOMER    ECOL168927:B0698-MONOMER   
KEGG: ecj:JW0686    eco:b0698   

Gene Ontology

GO:0016021 C:integral to membrane
GO:0005886 C:plasma membrane
GO:0005524 F:ATP binding
GO:0030955 F:potassium ion binding
GO:0008556 F:potassium-transporting ATPase activity
GO:0006813 P:potassium ion transport

References (5)

[1] “Sequence homology between two membrane transport ATPases, the Kdp-ATPase of Escherichia coli and the Ca2+-ATPase of sarcoplasmic reticulum.”  Hesse J.E.et.al.   6146979
[2] “A 718-kb DNA sequence of the Escherichia coli K-12 genome corresponding to the 12.7-28.0 min region on the linkage map.”  Oshima T.et.al.   8905232
[3] “The complete genome sequence of Escherichia coli K-12.”  Blattner F.R.et.al.   9278503
[4] “Highly accurate genome sequences of Escherichia coli K-12 strains MG1655 and W3110.”  Hayashi K.et.al.   16738553
[5] “Global topology analysis of the Escherichia coli inner membrane proteome.”  Daley D.O.et.al.   15919996
Structure:
5MRW   6HRA   6HRB     

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Predict TMSs (Predict number of transmembrane segments)
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FASTA formatted sequence
1:	MAAQGFLLIA TFLLVLMVLA RPLGSGLARL INDIPLPGTT GVERVLFRAL GVSDREMNWK 
61:	QYLCAILGLN MLGLAVLFFM LLGQHYLPLN PQQLPGLSWD LALNTAVSFV TNTNWQSYSG 
121:	ETTLSYFSQM AGLTVQNFLS AASGIAVIFA LIRAFTRQSM STLGNAWVDL LRITLWVLVP 
181:	VALLIALFFI QQGALQNFLP YQAVNTVEGA QQLLPMGPVA SQEAIKMLGT NGGGFFNANS 
241:	SHPFENPTAL TNFVQMLAIF LIPTALCFAF GEVMGDRRQG RMLLWAMSVI FVICVGVVMW 
301:	AEVQGNPHLL ALGTDSSINM EGKESRFGVL VSSLFAVVTT AASCGAVIAM HDSFTALGGM 
361:	VPMWLMQIGE VVFGGVGSGL YGMMLFVLLA VFIAGLMIGR TPEYLGKKID VREMKLTALA 
421:	ILVTPTLVLM GAALAMMTDA GRSAMLNPGP HGFSEVLYAV SSAANNNGSA FAGLSANSPF 
481:	WNCLLAFCMF VGRFGVIIPV MAIAGSLVSK KSQAASSGTL PTHGPLFVGL LIGTVLLVGA 
541:	LTFIPALALG PVAEYLS