Publication: Occupancy of nonannular lipid binding sites on KcsA greatly increases the stability of the tetrameric protein
Loading...
Date
2010-05-19
Authors
Triano García, Irene ; Barrera Olivares, Francisco Nicolás ; Renart Pérez, María Lourdes ; Molina Gallego, María Luisa ; Fernández Ballester, Gregorio ; Poveda Larrosa, José Antonio ; Fernández Carvajal, Asia María ; Encinar Hidalgo, José Antonio ; Ferrer Montiel, Antonio Vicente ; Otzen, Daniel ; González Ros, José Manuel
item.page.secondaryauthor
item.page.director
Publisher
American Chemical Society
publication.page.editor
publication.page.department
DOI
https://doi.org/10.1021/bi1003712
item.page.type
info:eu-repo/semantics/article
Description
© 2010 American Chemical Society. This document is the Published version of a Published Work that appeared in final form in Biochemistry. To access the final edited and published work see https://doi.org/10.1021/bi1003712
Abstract
KcsA, a homotetrameric potassium channel from prokaryotes, contains noncovalently bound lipids appearing in the X-ray crystallographic structure of the protein. The binding sites for such high-affinity lipids are referred to as “nonannular” sites, correspond to intersubunit protein domains, and bind preferentially anionic phospholipids. Here we used a thermal denaturation assay and detergent−phospholipid mixed micelles containing KcsA to study the effects of different phospholipids on protein stability. We found that anionic phospholipids stabilize greatly the tetrameric protein against irreversible, heat-induced unfolding and dissociation into subunits. This occurs in a phospholipid concentration-dependent manner, and phosphatidic acid species with acyl chain lengths ranging 14 to 18 carbon atoms are more efficient than similar phosphatidylglycerols in protecting the protein. A docking model of the KcsA−phospholipid complex suggests that the increased protein stability originates from the intersubunit nature of the binding sites and, thus, interaction of the phospholipid with such sites holds together adjacent subunits within the tetrameric protein. We also found that simpler amphiphiles, such as alkyl sulfates longer than 10 carbon atoms, also increase the protein stability to the same extent as anionic phospholipids, although at higher concentrations than the latter. Modeling the interaction of these simpler amphiphiles with KcsA and comparing it with that of anionic phospholipids serve to delineate the features of a hydrophobic pocket in the nonannular sites. Such pocket is predicted to comprise residues from the M2 transmembrane segment of a subunit and from the pore helix of the adjacent subunit and seems most relevant to protein stabilization.
publication.page.subject
Citation
Biochemistry 2010, 49, 25, 5397–5404
item.page.embargo
Collections
Ir a Estadísticas
Sin licencia Creative Commons.