1D9G: Bovine Interferon-gamma At 2.9 Angstroms

Citation:
Abstract
The structure of bovine interferon-gamma (IFN-gamma) was determined by multiple isomorphous replacement at 2.0 A resolution. Bovine IFN-gamma crystallizes in two related crystal forms. Crystal form 1 diffracts to 2.9 A resolution and is reproducible and stable to derivatization. Crystal form 2 diffracts to 2.0 A resolution, but shows significant non-isomorphism from crystal to crystal. The previously determined structures of several different species of INF-gamma were either at too low a resolution [human, 1hig; Ealick et al. (1991), Science, 252, 698-702] or were too inaccurate [bovine, 1rfb; Samudzi & Rubin (1993), Acta Cryst. D49(6), 505-512; rabbit, 2rig; Samudzi et al. (1991), J. Biol. Chem. 266(32), 21791-21797] for the structure to be solved by molecular replacement. The structure was solved in crystal form 1 using two derivatives produced by chemically modifying two free cysteine residues that were introduced by site-directed mutagenesis (Ser30Cys, Asn59Cys). After model building and refinement, the final R value was 21.8% (R(free) = 30.9%) for all data in the resolution range 8.0-2.9 A. The crystal form 1 structure was then used as a molecular-replacement model for crystal form 2 data collected from a flash-cooled crystal. Subsequent model building and refinement, using all data in the resolution range 15.0-2.0 A, gave an R value of 19.7% and an R(free) of 27.5%. Pairwise comparison of C(alpha) positions of bovine IFN-gamma (BOV) and the previously determined 1rfb and 2rig structures indicated some significant differences in the models (r.m.s.d. values for BOV to 1rfb, 4.3 A; BOV to 2rig, 4.0 A). An assessment of the quality of the structures was made using the 3D-1D algorithm [Eisenberg et al. (1992), Faraday Discuss. 93, 25-34]. The resulting statistical scoring indicated that BOV was consistent with expected criteria for a 2.0 A structure, whereas both 1rfb and 2rig fell below acceptable criteria.
PDB ID: 1D9GDownload
MMDB ID: 11616
PDB Deposition Date: 1999/10/27
Updated in MMDB: 1999/12
Experimental Method:
x-ray diffraction
Resolution: 2.9  Å
Source Organism:
Similar Structures:
Biological Unit for 1D9G: dimeric; determined by author and by software (PISA)
Molecular Components in 1D9G
Label Count Molecule
Proteins (2 molecules)
2
Interferon-gamma(Gene symbol: IFNG)
Molecule annotation
* Click molecule labels to explore molecular sequence information.

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