Does the KdpA subunit from the high affinity K+-translocating P-type KDP-ATPase have a structure similar to that of K+ channels?
Autor(en): | Durell, SR Bakker, EP Guy, HR |
Stichwörter: | Biophysics; HKT1; POTASSIUM CHANNEL; TRANSPORT ATPASES | Erscheinungsdatum: | 2000 | Herausgeber: | CELL PRESS | Enthalten in: | BIOPHYSICAL JOURNAL | Band: | 78 | Ausgabe: | 1, 1 | Startseite: | 188 | Seitenende: | 199 | Zusammenfassung: | Evidence is presented that the transmembrane KdpA subunit of the high affinity K+-translocating P-type Kdp-ATPase is evolutionarily derived from the superfamily of 2TM-type K+ channels in bacteria. This extends a previous study relating the K+ channels to the KtrAB, Trk, Trk1,2, and HKT1 K+ symporter superfamily of both prokaryotes and eukaryotes, Although the channels are formed by four single-MPM motif subunits, the transmembrane KdpA subunit and the transmembrane subunit of the symporter proteins are postulated to have four corresponding MPM motifs within a single sequence. Analysis of 17 KdpA sequences reveals a pattern of residue conservation similar to that of the symporters and channels, and consistent with the crystal structure of the KcsA K+ channel. In addition, the most highly conserved residues between the families, specifically the central glycines of the P2 segments, are those previously identified as crucial for the property of K+-selectivity that is common to each protein. This hypothesis is consistent with an experimental study of mutations that alter K+ binding affinity of the Kdp transporter. Although most of the results of a previous study of the transmembrane topology of KdpA are consistent with the 4-MPM model, the one deviation can be explained by a plausible change in the structure due to the experimental method. |
ISSN: | 00063495 | DOI: | 10.1016/S0006-3495(00)76584-2 |
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geprüft am 09.06.2024