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Title: The RCK Domain of the KtrAB K+ Transporter: Multiple Conformations of an Octameric Ring

Abstract

The KtrAB ion transporter is a complex of the KtrB membrane protein and KtrA, an RCK domain. RCK domains regulate eukaryotic and prokaryotic membrane proteins involved in K{sup +} transport. Conflicting functional models have proposed two different oligomeric arrangements for RCK domains, tetramer versus octamer. Our results for the KtrAB RCK domain clearly show an octamer in solution and in the crystal. We determined the structure of this protein in three different octameric ring conformations that resemble the RCK-domain octamer observed in the MthK potassium channel but show striking differences in size and symmetry. We present experimental evidence for the association between one RCK octameric ring and two KtrB membrane proteins. These results provide insights into the quaternary organization of the KtrAB transporter and its mechanism of activation and show that the RCK-domain octameric ring model is generally applicable to other ion-transport systems.

Authors:
; ; ; ;
Publication Date:
Research Org.:
Brookhaven National Laboratory (BNL) National Synchrotron Light Source
Sponsoring Org.:
Doe - Office Of Science
OSTI Identifier:
930250
Report Number(s):
BNL-80941-2008-JA
Journal ID: ISSN 0092-8674; CELLB5; TRN: US200822%%1422
DOE Contract Number:
DE-AC02-98CH10886
Resource Type:
Journal Article
Resource Relation:
Journal Name: Cell; Journal Volume: 126; Journal Issue: 6
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; FUNCTIONAL MODELS; IONS; MEMBRANE PROTEINS; POTASSIUM; PROTEINS; RINGS; SIZE; SOLUTIONS; SYMMETRY; TRANSPORT; national synchrotron light source

Citation Formats

Albright,R., Vazquez Ibar, J., Kim, C., Gruner, S., and Morais-Cabral, J. The RCK Domain of the KtrAB K+ Transporter: Multiple Conformations of an Octameric Ring. United States: N. p., 2006. Web. doi:10.1016/j.cell.2006.08.028.
Albright,R., Vazquez Ibar, J., Kim, C., Gruner, S., & Morais-Cabral, J. The RCK Domain of the KtrAB K+ Transporter: Multiple Conformations of an Octameric Ring. United States. doi:10.1016/j.cell.2006.08.028.
Albright,R., Vazquez Ibar, J., Kim, C., Gruner, S., and Morais-Cabral, J. Sun . "The RCK Domain of the KtrAB K+ Transporter: Multiple Conformations of an Octameric Ring". United States. doi:10.1016/j.cell.2006.08.028.
@article{osti_930250,
title = {The RCK Domain of the KtrAB K+ Transporter: Multiple Conformations of an Octameric Ring},
author = {Albright,R. and Vazquez Ibar, J. and Kim, C. and Gruner, S. and Morais-Cabral, J.},
abstractNote = {The KtrAB ion transporter is a complex of the KtrB membrane protein and KtrA, an RCK domain. RCK domains regulate eukaryotic and prokaryotic membrane proteins involved in K{sup +} transport. Conflicting functional models have proposed two different oligomeric arrangements for RCK domains, tetramer versus octamer. Our results for the KtrAB RCK domain clearly show an octamer in solution and in the crystal. We determined the structure of this protein in three different octameric ring conformations that resemble the RCK-domain octamer observed in the MthK potassium channel but show striking differences in size and symmetry. We present experimental evidence for the association between one RCK octameric ring and two KtrB membrane proteins. These results provide insights into the quaternary organization of the KtrAB transporter and its mechanism of activation and show that the RCK-domain octameric ring model is generally applicable to other ion-transport systems.},
doi = {10.1016/j.cell.2006.08.028},
journal = {Cell},
number = 6,
volume = 126,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}