title: Structural and dynamic characterization of intrinsically disordered human securin by NMR spectroscopy.
abstract: 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.
authors.affiliation: Institute of Enzymology, Biological Research Center, Hungarian Academy of Sciences, Budapest, Karolina ut 29, H-1113, Hungary.
authors.forename: Veronika
authors.initials: V
authors.lastname: Csizmok
authors.forename: Isabella C
authors.initials: IC
authors.lastname: Felli
authors.forename: Peter
authors.initials: P
authors.lastname: Tompa
authors.forename: Lucia
authors.initials: L
authors.lastname: Banci
authors.forename: Ivano
authors.initials: I
authors.lastname: Bertini
mesh_terms: 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
chemical_list: D018797:Cell Cycle Proteins; D009363:Neoplasm Proteins; D064249:Securin; C578002:pituitary tumor-transforming protein 1, human; D010450:Endopeptidases; C577987:ESPL1 protein, human; D064247:Separase