The role of calcium in the conformational changes of the recombinant S100A8/S100A91

Calprotectin is a member of the EF-hand proteins, composed of two subunits, S100A8 (MRP8) and S100A9 (MRP14). These proteins are involved in important processes including cell signaling, regulation of inflammatory responses, cell cycle control, differentiation, regulation of ion channel activity and...

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Bibliographic Details
Published in:Molecular biology (New York) 2016, Vol.50 (1), p.118-123
Main Authors: Gheibi, N., Asghari, H., Chegini, K. G., Sahmani, M., Moghadasi, M.
Format: Article
Language:English
Subjects:
Biochemistry
Biomedical and Life Sciences
Calcium
Cellular biology
Escherichia coli
Human Genetics
Life Sciences
Protein expression
Structural and Functional Analysis of Biopolymers and Biopolymer Complexes
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Summary:Calprotectin is a member of the EF-hand proteins, composed of two subunits, S100A8 (MRP8) and S100A9 (MRP14). These proteins are involved in important processes including cell signaling, regulation of inflammatory responses, cell cycle control, differentiation, regulation of ion channel activity and defense against microbial agents in a calcium dependent manner. In the present study, recombinant S100A8 and S100A9 were expressed in E. coli BL21 and then purified using Ni-NTA affinity chromatography. The structure of the S100A8/A9 complex in the presence and absence of calcium was assessed by circular dichroism and fluorescence spectroscopy. The intrinsic fluorescence emission spectra of the S100A8/A9 complex in the presence of calcium showed a reduction in fluorescence intensity, reflecting conformational changes within the protein with the exposure of aromatic residues to the protein surface. The far ultraviolet-circular dichroism spectra of the complex in the presence of calcium revealed minor changes in the regular secondary structure of the complex. Also, increased thermal stability of the S100A8/A9 complex in the presence of calcium was indicated.
ISSN:0026-8933
1608-3245
DOI:10.1134/S0026893315060084