1fia
From Proteopedia
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CRYSTAL STRUCTURE OF THE FACTOR FOR INVERSION STIMULATION FIS AT 2.0 ANGSTROMS RESOLUTION
Overview
The factor for inversion stimulation (FIS) binds as a homodimeric molecule, to a loose 15 nucleotide consensus sequence in DNA. It stimulates, DNA-related processes, such as DNA inversion and excision, it activates, transcription of tRNA and rRNA genes and it regulates its own synthesis., FIS crystallizes as a homodimer, with 2 x 98 amino acid residues in the, asymmetric unit. The crystal structure was determined with multiple, isomorphous replacement and refined to an R-factor of 19.2% against all, the 12,719 X-ray data (no sigma-cutoff) extending to 2.0 A resolution. The, two monomers are related by a non-crystallographic dyad axis. The, structure of the dimer is modular, with the first 23 amino acid residues, in molecule M1 and the first 24 in molecule M2 disordered and not "seen", in the electron density. The polypeptide folds into four alpha-helices, with alpha A, alpha A' (amino acid residues 26 to 40) and alpha B, alpha, B' (49 to 69) forming the core of the FIS dimer, which is stabilized by, hydrophobic forces. To the core are attached "classical" helix-turn-helix, motifs, alpha C, alpha D (73 to 81 and 84 to 94) and alpha C', alpha D'., The connections linking the helices are structured by two beta-turns for, alpha A/alpha B, and alpha C1 type extensions are observed at the C, termini of helices alpha B, alpha C and alpha D. Helices alpha D and alpha, D' contain 2 x 6 positive charges; they are separated by 24 A and can bind, adjacent major grooves in B-type DNA if it is bent 90 degrees. The modular, structure of FIS is also reflected by mutation experiments; mutations in, the N-terminal part and alpha A interfere with FIS binding to invertases, and mutations in the helix-turn-helix motif interfere with DNA binding.
About this Structure
1FIA is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
Reference
Crystal structure of the factor for inversion stimulation FIS at 2.0 A resolution., Kostrewa D, Granzin J, Stock D, Choe HW, Labahn J, Saenger W, J Mol Biol. 1992 Jul 5;226(1):209-26. PMID:1619650
Page seeded by OCA on Tue Nov 20 14:56:48 2007
