Download MendeleyCrystal structure of an mRNA-binding fragment of Moorella thermoacetica elongation factor SelB.
Selmer, M., Su, X.D.(2002) EMBO J 21: 4145-4153
- PubMed: 12145214
- DOI: https://doi.org/10.1093/emboj/cdf408
- Primary Citation of Related Structures:
1LVA - PubMed Abstract:
SelB is an elongation factor needed for the co-translational incorporation of selenocysteine. Selenocysteine is coded by a UGA stop codon in combination with a specific downstream mRNA hairpin. In bacteria, the C-terminal part of SelB recognizes this hairpin, while the N-terminal part binds GTP and tRNA in analogy with elongation factor Tu (EF-Tu). We present the crystal structure of a C-terminal fragment of SelB (SelB-C) from Moorella thermoacetica at 2.12 A resolution, solved by a combination of selenium and yttrium multiwavelength anomalous dispersion. This 264 amino acid fragment contains the entire C-terminal extension beginning after the EF-Tu-homologous domains. SelB-C consists of four similar winged-helix domains arranged into the shape of an L. This is the first example of winged-helix domains involved in RNA binding. The location of conserved basic amino acids, together with data from the literature, define the position of the mRNA-binding site. Steric requirements indicate that a conformational change may occur upon ribosome interaction. Structural observations and data in the literature suggest that this change happens upon mRNA binding.
Organizational Affiliation:
Department of Molecular Biophysics, Lund University, PO Box 124, S-221 00 Lund, Sweden. maria@mrc-lmb.cam.ac.uk
