Structural and dynamic characterization of intrinsically disordered human securin by NMR spectroscopy.
Understanding the molecular action of securin, the inhibitor of separase in mitosis, is of immense theoretical and biomedical importance. The residue-level structural description of an intrinsically disordered protein of this length (202 amino acids, containing 24 prolines), however, represents a particular challenge. Here we combined (1)H-detected and (13)C-detected protonless NMR experiments to achieve full assignment of securin's backbone amide resonances. Chemical shifts, (15)N relaxation rates (R(1), R(2), (1)H-(15)N NOEs), (1)H exchange rates with the solvent (CLEANEX-PM), and (1)H-(15)N residual dipolar couplings were determined along the entire length of the protein. This analysis showed that securin is not entirely disordered, but segregates into a largely disordered N-terminal half and a C-terminal half with transient segmental order, within which the segment D(150)-F(159) has a significant helical tendency and segments E(113)-S(127) and W(174)-L(178) also show a significant deviation from random-coil behavior. These results, in combination with bioinformatic and biochemical data on the securin/separase interaction, shed light on the inhibitory action of securin on separase.
Csizmok
Veronika
V
Institute of Enzymology, Biological Research Center, Hungarian Academy of Sciences, Budapest, Karolina ut 29, H-1113, Hungary.
Felli
Isabella C
IC
Tompa
Peter
P
Banci
Lucia
L
Bertini
Ivano
I
D000465:Algorithms; D018797:Cell Cycle Proteins / Q000378:metabolism; D010450:Endopeptidases / Q000378:metabolism; D006801:Humans; D009363:Neoplasm Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D019906:Nuclear Magnetic Resonance, Biomolecular; D064249:Securin; D064247:Separase
D018797:Cell Cycle Proteins; D009363:Neoplasm Proteins; D064249:Securin; C578002:pituitary tumor-transforming protein 1, human; D010450:Endopeptidases; C577987:ESPL1 protein, human; D064247:Separase