title: High-resolution NMR studies of structure and dynamics of human ERp27 indicate extensive interdomain flexibility.
abstract: ERp27 (endoplasmic reticulum protein 27.7 kDa) is a homologue of PDI (protein disulfide-isomerase) localized to the endoplasmic reticulum. ERp27 is predicted to consist of two thioredoxin-fold domains homologous with the non-catalytic b and b' domains of PDI. The structure in solution of the N-terminal b-like domain of ERp27 was solved using high-resolution NMR data. The structure confirms that it has the thioredoxin fold and that ERp27 is a member of the PDI family. (15)N-NMR relaxation data were obtained and ModelFree analysis highlighted limited exchange contributions and slow internal motions, and indicated that the domain has an average order parameter S(2) of 0.79. Comparison of the single-domain structure determined in the present study with the equivalent domain within full-length ERp27, determined independently by X-ray diffraction, indicated very close agreement. The domain interface inferred from NMR data in solution was much more extensive than that observed in the X-ray structure, suggesting that the domains flex independently and that crystallization selects one specific interdomain orientation. This led us to apply a new rapid method to simulate the flexibility of the full-length protein, establishing that the domains show considerable freedom to flex (tilt and twist) about the interdomain linker, consistent with the NMR data.
authors.affiliation: School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK.
authors.forename: Nader T
authors.initials: NT
authors.lastname: Amin
authors.forename: A Katrine
authors.initials: AK
authors.lastname: Wallis
authors.forename: Stephen A
authors.initials: SA
authors.lastname: Wells
authors.forename: Michelle L
authors.initials: ML
authors.lastname: Rowe
authors.forename: Richard A
authors.initials: RA
authors.lastname: Williamson
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Howard
authors.forename: Robert B
authors.initials: RB
authors.lastname: Freedman
mesh_terms: D001665:Binding Sites; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D006360:Heat-Shock Proteins / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D019704:Protein Disulfide-Isomerases / Q000737:chemistry* / Q000378:metabolism; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D014961:X-Ray Diffraction
chemical_list: D006360:Heat-Shock Proteins; C579647:ERp27 protein, human; D019704:Protein Disulfide-Isomerases