Calcium-dependent structural changes in human reticulocalbin-1.
Human reticulocalbin-1 (hRCN1) has six EF-hand motifs and binds Ca(2+). hRCN1 is a member of the CREC family localized in the secretory pathway, and its cellular function remains unclear. In this study, we established a new bacterial expression and purification procedure for hRCN1. We observed that hRCN1 binds Ca(2+) in a cooperative manner and the Ca(2+) binding caused an increase in the α-helix content of hRCN1. On the other hand, hRCN1 did not change the structure with Mg(2+) loading. hRCN1 is a monomeric protein, and its overall structure became more compact upon Ca(2+) binding, as revealed by gel-filtration column chromatography and small-angle X-ray scattering. This is the first report of conformational changes in the CREC family upon Ca(2+) binding. Our data suggest that CREC family member interactions with target proteins are regulated in the secretory pathway by conformational changes upon Ca(2+) binding.
Department of Chemistry, Graduate School of Science, Chiba University, Chiba 263-8522, Japan; Department of Applied Biological Chemistry, Graduate School of Agricultural and Life Sciences, University of Tokyo, Tokyo 113-8657, Japan; and Laboratory of Chemistry, College of Liberal and Sciences, Tokyo Medical and Dental University, Chiba 272-0827, Japan.
Nanao
N
Suzuki
Syoko
S
Ban
Eriko
E
Itoh
Sisi
S
Chen
Fabiana L
FL
Imai
Yoriko
Y
Sawano
Takuya
T
Miyakawa
Masaru
M
Tanokura
Naoto
N
Yonezawa
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D002118:Calcium / Q000378:metabolism*; D002135:Calcium-Binding Proteins / Q000737:chemistry* / Q000378:metabolism*; D002850:Chromatography, Gel; D004926:Escherichia coli / Q000235:genetics; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008274:Magnesium / Q000378:metabolism; D008969:Molecular Sequence Data; D011487:Protein Conformation; D012542:Scattering, Radiation; D017386:Sequence Homology, Amino Acid
D002135:Calcium-Binding Proteins; C000597745:RCN1 protein, human; D008274:Magnesium; D002118:Calcium
CREC family; Ca2+-binding; EF-hand motif; human reticulocalbin-1; small-angle X-ray scattering