15N NMR relaxation studies of calcium-loaded parvalbumin show tight dynamics compared to those of other EF-hand proteins.
Dynamics of the rat alpha-parvalbumin calcium-loaded form have been determined by measurement of 15N nuclear relaxation using proton-detected heteronuclear NMR spectroscopy. The relaxation data were analyzed using spectral density functions and the Lipari-Szabo formalism. The major dynamic features for the rat alpha-parvalbumin calcium-loaded form are (1) the extreme rigidity of the helix-loop-helix EF-hand motifs and the linker segment connecting them, (2) the N and C termini of the protein being restricted in their mobility, (3) a conformational exchange occurring at the kink of helix D, and (4) the residue at relative position 2 in the Ca2+-binding sites having an enhanced mobility. Comparison of the Ca2+-binding EF-hand domains of alpha-parvalbumin-Ca2+, calbindin-Ca2+, and calmodulin-Ca2+ shows that parvalbumin is probably the most rigid of the EF-hand proteins. It also illustrates the dynamical properties which are conserved in the EF-hand domains from different members of this superfamily: (1) a tendency toward higher mobility of NH vectors at relative position 2 in the Ca2+-binding loop, (2) a restricted mobility for the other residues in the binding loop, and (3) an overall rigidity for the helices of EF-hand motifs. The differences in mobility between parvalbumin and the two EF-hand proteins occur mainly at the linker connecting the pair of EF hands and also at the C terminus of the last helix. In parvalbumin-Ca2+, these two regions are characterized by a pronounced rigidity compared to the corresponding more mobile regions in calbindin-Ca2+ and calmodulin-Ca2+.
Centre de Biochimie Structurale, Faculté de Pharmacie, CNRS UMR 9955-INSERM U414, Montpellier, France.
C
C
Baldellon
J R
JR
Alattia
M P
MP
Strub
T
T
Pauls
M W
MW
Berchtold
A
A
Cavé
A
A
Padilla
D000577:Amides; D000818:Animals; D002135:Calcium-Binding Proteins / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D009587:Nitrogen Isotopes; D019906:Nuclear Magnetic Resonance, Biomolecular; D010320:Parvalbumins / Q000737:chemistry* / Q000378:metabolism; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D011522:Protons; D051381:Rats; D013816:Thermodynamics
D000577:Amides; D002135:Calcium-Binding Proteins; D009587:Nitrogen Isotopes; D010320:Parvalbumins; D011522:Protons