C-terminal half of human centrin 2 behaves like a regulatory EF-hand domain.
Human centrin 2 (HsCen2) is an EF-hand protein that plays a critical role in the centrosome duplication and separation during cell division. We studied the structural and Ca(2+)-binding properties of two C-terminal fragments of this protein: SC-HsCen2 (T94-Y172), covering two EF-hands, and LC-HsCen2 (M84-Y172), having 10 additional residues. Both fragments are highly disordered in the apo state but become better structured (although not conformationally homogeneous) in the presence of Ca(2+) and depending on the nature of the cations (K(+) or Na(+)) in the buffer. Only the longer C-terminal domain, in the Ca(2+)-saturated state and in the presence of Na(+) ions, was amenable to structure determination by nuclear magnetic resonance. The solution structure of LC-HsCen2 reveals an open two EF-hand structure, similar to the conformation of related Ca(2+)-saturated regulatory domains. Unexpectedly, the N-terminal helix segment (F86-T94) lies over the exposed hydrophobic cavity. This unusual intramolecular interaction increases considerably the Ca(2+) affinity and constitutes a useful model for the target binding.
Matei
Elena
E
INSERM U350 and Institut Curie-Recherche, Centre Universitaire, Bâtiments 110-112, 91405 Orsay, France.
Miron
Simona
S
Blouquit
Yves
Y
Duchambon
Patricia
P
Durussel
Isabelle
I
Cox
Jos A
JA
Craescu
Constantin T
CT
D000595:Amino Acid Sequence; D000818:Animals; D002118:Calcium / Q000737:chemistry; D002135:Calcium-Binding Proteins; D018797:Cell Cycle Proteins / Q000737:chemistry* / Q000502:physiology; D016825:Chlamydomonas reinhardtii / Q000737:chemistry; D018360:Crystallography, X-Ray; D020832:EF Hand Motifs / Q000502:physiology; D006801:Humans; D008555:Melitten / Q000737:chemistry; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D010446:Peptide Fragments / Q000737:chemistry* / Q000502:physiology; D011485:Protein Binding; D011487:Protein Conformation; D017434:Protein Structure, Tertiary / Q000502:physiology; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013050:Spectrometry, Fluorescence; D013816:Thermodynamics
C472752:CETN2 protein, human; D002135:Calcium-Binding Proteins; D018797:Cell Cycle Proteins; D010446:Peptide Fragments; D008555:Melitten; D002118:Calcium