Mouse S100G protein exhibits properties characteristic of a calcium sensor. (May 2020)

• Record Type: Journal Article
• Authors: Permyakov, Sergei E.; Yundina, Elena N.; Kazakov, Alexei S.; Permyakova, Maria E.; Uversky, Vladimir N.; Permyakov, Eugene A.
• Is Part Of: Cell calcium. Volume 87(2020)
• Publication Date: 2020-05
• Subjects: CD circular dichroism spectroscopy -- DSC differential scanning calorimetry -- EDTA ethylenediaminetetraacetic acid -- EGTA ethylene glycolbis(2-aminoethylether)-N, N, N', N'-tetraacetic acid -- ESI-MS electrospray ionization mass spectrometry -- GdnHCl guanidine hydrochloride -- HEPES N-(2-hydroxyethyl) piperazineN'-(2-ethanesulfonic acid) -- IPTG isopropyl β-d-1-thiogalactopyranoside -- NMR nuclear magnetic resonance -- PMSF phenylmethanesulfonyl fluoride -- PPRD percent of predicted disordered residues -- TCA trichloroacetic acid -- Tris tris(hydroxymethyl) aminomethane -- SDS-PAGE sodium dodecyl sulfate polyacrylamide gel electrophoresis; S100G -- Calmodulin -- Calcium sensor -- EF-hand -- Intrinsic disorder; Calcium -- Metabolism -- Periodicals; Vertebrates -- Physiology -- Periodicals; Calcium -- Physiological effect -- Periodicals; Cell physiology -- Periodicals; Calcium in the body -- Periodicals; 572.516
• DOI: 10.1016/j.ceca.2020.102185
• Languages: English
• ISSNs: 0143-4160

Abstract

Graphical abstract: Highlights: Mouse S100 G is a member of the EF-hand family of calcium binding proteins. Contrary to bovine S100 G structure and function of mouse protein depends on calcium. Based on its response to calcium, mouse S100 G is classified as calcium sensor protein. Apo-form of mouse S100 G has the properties of highly ordered molten globule. Mouse S100 G is predicted to contain high levels of intrinsic disorder. Abstract: Bovine S100 G (calbindin D9k, small Ca 2+ -binding protein of the EF-hand superfamily) is considered as a calcium buffer protein; i.e., the binding of Ca 2+ practically does not change its general conformation. A set of experimental approaches has been used to study structural properties of apo- and Ca 2+ -loaded forms of mouse S100 G (81.4% identity in amino acid sequence with bovine S100 G). This analysis revealed that, in contrast to bovine S100 G, the removal of calcium ions increases α-helices content of mouse S100 G protein and enhances its accessibility to digestion by α-chymotrypsin. Furthermore, mouse apo-S100 G is characterized by a decreased surface hydrophobicity and reduced tendency for oligomerization. Such behavior is typical of calcium sensor proteins. Apo-state of mouse S100 G still has rather compact structure, which can be cooperatively unfolded by temperature and GdnHCl. Computational analysis of amino acid sequences of S100 G proteins shows that these proteins could be in a disordered state upon a removal of the bound calcium ions. The experimental data show that, although mouse apo-S100 G is flexible compared to the Ca 2+ -loaded state, the apo-form is not completely disordered and preserves some cooperatively meting structure. The origin of the unexpectedly high stability of mouse S100 G can be rationalized by an exceptionally strong association of its N- and C-terminal parts containing the EF-hands I and II, respectively.