Transition metal ion FRET uncovers K⁺ regulation of a neurotransmitter/sodium symporter.

ABSTRACT: Neurotransmitter/sodium symporters (NSSs) are responsible for Na⁺-dependent reuptake of neurotransmitters and represent key targets for antidepressants and psychostimulants. LeuT, a prokaryotic NSS protein, constitutes a primary structural model for these transporters. Here we show that K⁺ inhibits Na⁺-dependent binding of substrate to LeuT, promotes an outward-closed/inward-facing conformation of the transporter and increases uptake. To assess K⁺-induced conformational dynamics we measured fluorescence resonance energy transfer (FRET) between fluorescein site-specifically attached to inserted cysteines and Ni²⁺ bound to engineered di-histidine motifs (transition metal ion FRET). The measurements supported K⁺-induced closure

SUBMITTER: Billesbolle CB 

PROVIDER: S-EPMC5052704 | biostudies-literature | 2016 Sep

REPOSITORIES: biostudies-literature