Calcium-induced conformational changes of the recombinant CBP3 protein from Dictyostelium discoideum.
Calcium-binding proteins play various and significant roles in biological systems. Conformational changes in their structures are closely related to their physiological functions. To understand the role of calcium-binding protein 3 (CBP3) in Dictyostelium discoideum, its recombinant proteins were analyzed using circular dichroism (CD) and fluorescence spectroscopy. Gel mobility shift analysis showed that Ca2+ induced a mobility shift of the recombinant CBP3. Far ultra-violet CD spectra and intrinsic fluorescence spectra on CBP3 and its N- and C-terminal domains exhibited that they underwent a conformational rearrangement depending upon Ca2+ binding. Measurement of Ca2+ dissociation constants demonstrated that CBP3 had high affinity toward Ca2+ in the sub-micromolar range and N-terminal domain had higher affinity than C-terminal domain. The changes of fluorescence spectra by an addition of 8-anilino-1-naphthalene sulfonic acid indicated that the hydrophobic patches of CBP3 and its C-terminal domain are likely to be more exposed in the presence of Ca2+. Since the exposure of hydrophobic patches is thermodynamically unfavorable, Ca2+-bound CBP3 may interact with other proteins in vivo. All these data suggest that Ca2+ induces CBP3 to be more favorable conformation to interact with target proteins.
Mishig-Ochiriin
Tsogbadrakh
T
Laboratory of Biophysics, School of Biological Sciences, Seoul National University, Seoul 151-742, South Korea.
Lee
Chang-Hun
CH
Jeong
Sun-Young
SY
Kim
Beom-Jun
BJ
Choi
Chang-Hoon
CH
Yim
Hyung-Soon
HS
Kang
Sa-Ouk
SO
D000595:Amino Acid Sequence; D000817:Anilino Naphthalenesulfonates / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000737:chemistry* / Q000378:metabolism; D002135:Calcium-Binding Proteins / Q000737:chemistry* / Q000378:metabolism; D002942:Circular Dichroism; D004023:Dictyostelium / Q000378:metabolism*; D004926:Escherichia coli / Q000378:metabolism; D007700:Kinetics; D008969:Molecular Sequence Data; D010957:Plasmids / Q000378:metabolism; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D015800:Protozoan Proteins / Q000737:chemistry* / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry*; D017386:Sequence Homology, Amino Acid; D013050:Spectrometry, Fluorescence; D013816:Thermodynamics; D014466:Ultraviolet Rays
D000817:Anilino Naphthalenesulfonates; C116578:CBP3 protein, Dictyostelium discoideum; D002135:Calcium-Binding Proteins; D015800:Protozoan Proteins; D011994:Recombinant Proteins; C027132:1-anilino-8-naphthalenesulfonate; D002118:Calcium