The KtrA and KtrE subunits are required for Na+-dependent K+ uptake by KtrB across the plasma membrane in Synechocystis sp. strain PCC 6803.

ABSTRACT: The Na+-dependent K+ uptake KtrABE system is essential for the adaptation of Synechocystis to salinity stress and high osmolality. While KtrB forms the K+-translocating pore, the role of the subunits KtrA and KtrE for Ktr function remains elusive. Here, we characterized the role of KtrA and KtrE in Ktr-mediated K+ uptake and in modulating Na+ dependency. Expression of KtrB alone in a K+ uptake-deficient Escherichia coli strain conferred low K+ uptake activity that was not stimulated by Na+. Coexpression of both KtrA and KtrE with KtrB increased the K+ transport activity in a Na+-dependent manner. KtrA and KtrE were found to be localized to the plasma membrane in Synechocystis. Site-directed mutagenesis was used to analyze the role of single charged residues in KtrB for Ktr function. Replac

SUBMITTER: Zulkifli L 

PROVIDER: S-EPMC2944510 | biostudies-literature | 2010 Oct

REPOSITORIES: biostudies-literature