Author(s): Szollosi, Andras ; Vieira-Pires, Ricardo S. ; Teixeira-Duarte, Celso M. ; Rocha, Rita ; Morais-Cabral, João H.
Date: 2016
Persistent ID: https://hdl.handle.net/10316/108776
Origin: Estudo Geral - Universidade de Coimbra
Subject(s): Adenosine Triphosphate; Bacillus subtilis; Bacterial Proteins; Cation Transport Proteins; Escherichia coli; Potassium; Protein Conformation
KtrAB belongs to the Trk/Ktr/HKT superfamily of monovalent cation (K+ and Na+) transport proteins that closely resemble K+ channels. These proteins underlie a plethora of cellular functions that are crucial for environmental adaptation in plants, fungi, archaea, and bacteria. The activation mechanism of the Trk/Ktr/HKT proteins remains unknown. It has been shown that ATP stimulates the activity of KtrAB while ADP does not. Here, we present X-ray structural information on the KtrAB complex with bound ADP. A comparison with the KtrAB-ATP structure reveals conformational changes in the ring and in the membrane protein. In combination with a biochemical and functional analysis, we uncover how ligand-dependent changes in the KtrA ring are propagated to the KtrB membrane protein and conclude that, despite their structural similarity, the activation mechanism of KtrAB is markedly different from the activation mechanism of K+ channels.
AS was supported by FEBS (Long term fellowship). This work was financially supported by national funds through FCT—Fundação para a Ciência e a Tecnologia/MEC—Ministério da Educação e Ciência and when applicable co-funded by FEDER funds within the Partnership Agreement PT2020 related with the research unit number 4293 and by FEDER funds through the Operational Competitiveness Program–COMPETE and by National Funds through FCT–Fundação para a Ciência e a Tecnologia under the project FCOMP-01- 0124-FEDER-028115 (PTDC/BBB-BEP/2017/2012).
