title: Resonance assignments, secondary structure and topology of leukaemia inhibitory factor in solution.
abstract: The chemical shift assignments and secondary structure of a murine-human chimera, MH35, of leukaemia inhibitory factor (LIF), a 180-residue protein of molecular mass 20 kDa, have been determined from multidimensional heteronuclear NMR spectra acquired on a uniformly 13C, 15N-labelled sample. Secondary structure elements were defined on the basis of chemical shifts, NH-C alpha H coupling constants; medium-range NOEs and the location of slowly exchanging amide protons. The protein contains four alpha-helices, the relative orientations of which were determined on the basis of long-range, interhelical NOEs. The four helices are arranged in an up-up-down-down orientation, as found in other four-helical bundle cytokines. The overall topology of MH35-LIF is similar to that of the X-ray crystallographic structure for murine LIF [Robinson et al. (1994) Cell, 77, 1101-1116]. Differences between the X-ray structure and the solution structure are evident in the N-terminal tail, where the solution structure has a trans-Pro17 compared with the cis-Pro17 found in the crystal structure and the small antiparallel beta-sheet encompassing residues in the N-terminus and CD loop in the crystal structure is less stable.
authors.affiliation: Biomolecular Research Institute, Parkville, VIC, Australia.
authors.forename: M G
authors.initials: MG
authors.lastname: Hinds
authors.forename: T
authors.initials: T
authors.lastname: Maurer
authors.forename: J G
authors.initials: JG
authors.lastname: Zhang
authors.forename: N A
authors.initials: NA
authors.lastname: Nicola
authors.forename: R S
authors.initials: RS
authors.lastname: Norton
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002247:Carbon Isotopes; D003001:Cloning, Molecular; D018360:Crystallography, X-Ray / Q000379:methods; D004926:Escherichia coli; D006131:Growth Inhibitors / Q000737:chemistry*; D006801:Humans; D015850:Interleukin-6; D053605:Leukemia Inhibitory Factor; D008222:Lymphokines / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D051379:Mice; D008961:Models, Structural; D008969:Molecular Sequence Data; D009587:Nitrogen Isotopes; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D011993:Recombinant Fusion Proteins / Q000737:chemistry; D017386:Sequence Homology, Amino Acid; D012996:Solutions
chemical_list: D002247:Carbon Isotopes; D006131:Growth Inhibitors; D015850:Interleukin-6; C507837:LIF protein, human; D053605:Leukemia Inhibitory Factor; C507838:Lif protein, mouse; D008222:Lymphokines; D009587:Nitrogen Isotopes; D011993:Recombinant Fusion Proteins; D012996:Solutions