Membrane accessibility of glutathione

Alvaro Garcia; Nasma D Eljack; Marc-Antoine Sani; Frances Separovic; Helge H Rasmussen; Wojciech Kopec; Himanshu Khandelia; Flemming Cornelius; Ronald J Clarke

doi:10.1016/j.bbamem.2015.07.016

Membrane accessibility of glutathione

Biochim Biophys Acta. 2015 Oct;1848(10 Pt A):2430-6. doi: 10.1016/j.bbamem.2015.07.016. Epub 2015 Jul 30.

Authors

Alvaro Garcia¹, Nasma D Eljack¹, Marc-Antoine Sani², Frances Separovic², Helge H Rasmussen³, Wojciech Kopec⁴, Himanshu Khandelia⁴, Flemming Cornelius⁵, Ronald J Clarke⁶

Affiliations

¹ School of Chemistry, University of Sydney, Sydney, New South Wales 2006, Australia.
² School of Chemistry, Bio21 Institute, University of Melbourne, Melbourne, Victoria 3010, Australia.
³ Department of Cardiology, Royal North Shore Hospital, Sydney, New South Wales 2065, Australia; Kolling Institute, University of Sydney, Sydney, New South Wales 2065, Australia.
⁴ Center for BioMembrane Physics, University of Southern Denmark, Odense M5230, Denmark.
⁵ Department of Biomedicine, University of Aarhus, DK-8000 Aarhus C, Denmark.
⁶ School of Chemistry, University of Sydney, Sydney, New South Wales 2006, Australia. Electronic address: ronald.clarke@sydney.edu.au.

PMID: 26232559
DOI: 10.1016/j.bbamem.2015.07.016

Abstract

Regulation of the ion pumping activity of the Na+,K+-ATPase is crucial to the survival of animal cells. Recent evidence has suggested that the activity of the enzyme could be controlled by glutathionylation of cysteine residue 45 of the β-subunit. Crystal structures so far available indicate that this cysteine is in a transmembrane domain of the protein. Here we have analysed via fluorescence and NMR spectroscopy as well as molecular dynamics simulations whether glutathione is able to penetrate into the interior of a lipid membrane. No evidence for any penetration of glutathione into the membrane was found. Therefore, the most likely mechanism whereby the cysteine residue could become glutathionylated is via a loosening of the α-β subunit association, creating a hydrophilic passageway between them to allow access of glutathione to the cysteine residue. By such a mechanism, glutathionylation of the protein would be expected to anchor the modified cysteine residue in a hydrophilic environment, inhibiting further motion of the β-subunit during the enzyme's catalytic cycle and suppressing enzymatic activity, as has been experimentally observed. The results obtained, therefore, suggest a possible structural mechanism of how the Na+,K+-ATPase could be regulated by glutathione.

Keywords: Beta-subunit; Glutathionylation; Phosphatidylcholine; Plasma membrane; Regulation; Sodium pump.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Glutathione / chemistry*
Lipid Bilayers / chemistry*
Models, Chemical*
Molecular Conformation
Molecular Dynamics Simulation*
Sodium-Potassium-Exchanging ATPase / chemistry*
Sodium-Potassium-Exchanging ATPase / ultrastructure*

Substances

Lipid Bilayers
Sodium-Potassium-Exchanging ATPase
Glutathione