Site-site communication in the EF-hand Ca2+-binding protein calbindin D9k.
The cooperative binding of Ca2+ ions is an essential functional property of the EF-hand family of Ca2+-binding proteins. To understand how these proteins function, it is essential to characterize intermediate binding states in addition to the apo- and holo-proteins. The three-dimensional solution structure and fast time scale internal motional dynamics of the backbone have been determined for the half-saturated state of the N56A mutant of calbindin D9k with Ca2+ bound only in the N-terminal site. The extent of conformational reorganization and a loss of flexibility in the C-terminal EF-hand upon binding of an ion in the N-terminal EF-hand provide clear evidence of the importance of site-site interactions in this family of proteins, and demonstrates the strength of long-range effects in the cooperative EF-hand Ca2+-binding domain.
Mäler
L
L
Department of Molecular Biology (MB9), The Scripps Research Institute, 10550 North Torrey Pines Road., La Jolla, California 92037, USA.
Blankenship
J
J
Rance
M
M
Chazin
W J
WJ
D000495:Allosteric Site; D019943:Amino Acid Substitution / Q000235:genetics; D001059:Apoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D064026:Calbindins; D002118:Calcium / Q000378:metabolism*; D020832:EF Hand Motifs; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009038:Motion; D019906:Nuclear Magnetic Resonance, Biomolecular; D018583:Pliability; D011485:Protein Binding; D011487:Protein Conformation; D064030:S100 Calcium Binding Protein G / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D012996:Solutions; D013816:Thermodynamics
D001059:Apoproteins; D064026:Calbindins; D064030:S100 Calcium Binding Protein G; D012996:Solutions; D002118:Calcium