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Adenosine Monophosphate Binding Stabilizes the KTN Domain of the Shewanella denitrificans Kef Potassium Efflux System

DOI: 10.1021/acs.biochem.7b00300 DOI Help

Authors: Christos Pliotas (University of St Andrews) , Samuel C. Grayer (University of Oxford) , Silvia Ekkerman (University of Aberdeen) , Anthony K. N. Chan (University of Oxford) , Jess Healy (University of Oxford) , Phedra Marius (University of St Andrews) , Wendy Bartlett (University of Aberdeen) , Amjad Khan (University of Oxford) , Wilian A. Cortopassi (University of Oxford) , Shane A. Chandler (University of Oxford) , Tim Rasmussen (University of Aberdeen) , Justin L. P. Benesch (University of Oxford) , Robert S. Paton (University of Oxford) , Timothy D. W. Claridge (University of Oxford) , Samantha Miller (University of Aberdeen) , Ian R. Booth (University of Aberdeen) , James Naismith (University of St Andrews; Sichuan University; RCaH) , Stuart J. Conway (University of Oxford; Albert-Ludwigs-Universität Freiburg)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Biochemistry , VOL 56 , PAGES 4219 - 4234

State: Published (Approved)
Published: August 2017

Open Access Open Access

Abstract: Ligand binding is one of the most fundamental properties of proteins. Ligand functions fall into three basic types: substrates, regulatory molecules, and cofactors essential to protein stability, reactivity, or enzyme–substrate complex formation. The regulation of potassium ion movement in bacteria is predominantly under the control of regulatory ligands that gate the relevant channels and transporters, which possess subunits or domains that contain Rossmann folds (RFs). Here we demonstrate that adenosine monophosphate (AMP) is bound to both RFs of the dimeric bacterial Kef potassium efflux system (Kef), where it plays a structural role. We conclude that AMP binds with high affinity, ensuring that the site is fully occupied at all times in the cell. Loss of the ability to bind AMP, we demonstrate, causes protein, and likely dimer, instability and consequent loss of function. Kef system function is regulated via the reversible binding of comparatively low-affinity glutathione-based ligands at the interface between the dimer subunits. We propose this interfacial binding site is itself stabilized, at least in part, by AMP binding.

Subject Areas: Biology and Bio-materials, Chemistry


Instruments: I24-Microfocus Macromolecular Crystallography

Documents:
acs.bioc5656hem.pdf

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