2PLY: Structure Of The Mrna Binding Fragment Of Elongation Factor Selb In Complex With Secis Rna

Elongation factor SelB is responsible for co-translational incorporation of selenocysteine (Sec) into proteins. The UGA stop codon is recoded as a Sec codon in the presence of a downstream mRNA hairpin. In prokaryotes, in addition to the EF-Tu-like N-terminal domains, a C-terminal extension containing four tandem winged-helix motifs (WH1-4) recognizes the mRNA hairpin. The 2.3-A resolution crystal structure of the Escherichia coli WH3/4 domains bound to mRNA with mutagenesis data reveal that the two WH motifs use the same structural elements to bind RNA. The structure together with the 2.6-A resolution structure of the WH1-4 domains from Moorella thermoacetica bound to RNA revealed that a salt bridge connecting WH2 to WH3 modules is disrupted upon mRNA binding. The results provide a structural basis for the molecular switch that may allow communication between tRNA and mRNA binding sites and illustrate how RNA acts as an activator of the switch. The structures show that tandem WH motifs not only provide an excellent scaffold for RNA binding but can also have an active role in the function of protein-RNA complexes.
PDB ID: 2PLYDownload
MMDB ID: 60528
PDB Deposition Date: 2007/4/20
Updated in MMDB: 2007/11
Experimental Method:
x-ray diffraction
Resolution: 2.6  Å
Source Organism:
synthetic construct
Similar Structures:
Biological Unit for 2PLY: dimeric; determined by author
Molecular Components in 2PLY
Label Count Molecule
Protein (1 molecule)
Selenocysteine-specific Elongation Factor
Molecule annotation
Nucleotide(1 molecule)
RNA (5'- R(*gp*gp*cp*gp*up*up*gp*cp*cp*gp*gp*up*cp*up*gp*gp*cp*ap*ap *cp*gp*cp*c)-3')
Molecule annotation
Chemicals (17 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB