Crystal structure of an mRNA-binding fragment of Moorella thermoacetica elongation factor SelB

AUTOR(ES)

Selmer, M.

FONTE

Oxford University Press

RESUMO

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 Å 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. Struc tural observations and data in the literature suggest that this change happens upon mRNA binding.

Documentos Relacionados

• In vitro and in vivo characterization of novel mRNA motifs that bind special elongation factor SelB
• Selenocysteine tRNA-specific elongation factor SelB is a structural chimaera of elongation and initiation factors
• A Family of Insulin-Like Growth Factor II mRNA-Binding Proteins Represses Translation in Late Development
• Rat lung contains a developmentally regulated manganese superoxide dismutase mRNA-binding protein.
• Sequence analysis of cytoplasmic mRNA-binding proteins of Xenopus oocytes identifies a family of RNA-binding proteins.