title: NMR spectroscopy of 14-3-3ζ reveals a flexible C-terminal extension: differentiation of the chaperone and phosphoserine-binding activities of 14-3-3ζ.
abstract: Intracellular 14-3-3 proteins bind to many proteins, via a specific phosphoserine motif, regulating diverse cellular tasks including cell signalling and disease progression. The 14-3-3ζ isoform is a molecular chaperone, preventing the stress-induced aggregation of target proteins in a manner comparable with that of the unrelated sHsps (small heat-shock proteins). 1H-NMR spectroscopy revealed the presence of a flexible and unstructured C-terminal extension, 12 amino acids in length, which protrudes from the domain core of 14-3-3ζ and is similar in structure and length to the C-terminal extension of mammalian sHsps. The extension stabilizes 14-3-3ζ, but has no direct role in chaperone action. Lys(49) is an important functional residue within the ligand-binding groove of 14-3-3ζ with K49E 14-3-3ζ exhibiting markedly reduced binding to phosphorylated and non-phosphorylated ligands. The R18 peptide binds to the binding groove of 14-3-3ζ with high affinity and also reduces the interaction of 14-3-3ζ ligands. However, neither the K49E mutation nor the presence of the R18 peptide affected the chaperone activity of 14-3-3ζ, implying that the C-terminal extension and binding groove of 14-3-3ζ do not mediate interaction with target proteins during chaperone action. Other region(s) in 14-3-3ζ are most likely to be involved, i.e. the protein's chaperone and phosphoserine-binding activities are functionally and structurally separated.
authors.affiliation: School of Chemistry and Physics, The University of Adelaide, Adelaide, SA 5005, Australia.
authors.forename: Danielle M
authors.initials: DM
authors.lastname: Williams
authors.forename: Heath
authors.initials: H
authors.lastname: Ecroyd
authors.forename: Katy L
authors.initials: KL
authors.lastname: Goodwin
authors.forename: Huanqin
authors.initials: H
authors.lastname: Dai
authors.forename: Haian
authors.initials: H
authors.lastname: Fu
authors.forename: Joanna M
authors.initials: JM
authors.lastname: Woodcock
authors.forename: Lixin
authors.initials: L
authors.lastname: Zhang
authors.forename: John A
authors.initials: JA
authors.lastname: Carver
mesh_terms: D048948:14-3-3 Proteins / Q000737:chemistry* / Q000378:metabolism*; D000595:Amino Acid Sequence; D004926:Escherichia coli / Q000378:metabolism; D006801:Humans; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D018832:Molecular Chaperones / Q000378:metabolism*; D008969:Molecular Sequence Data; D010768:Phosphoserine / Q000378:metabolism*; D011485:Protein Binding; D020798:Two-Hybrid System Techniques
chemical_list: D048948:14-3-3 Proteins; D018832:Molecular Chaperones; D010768:Phosphoserine