Conformational switches in winged-helix domains 1 and 2 of bacterial translation elongation factor SelB.
The crystal structure of the first two winged-helix motifs of translation elongation factor SelB from Moorella thermoacetica has been determined at 1.1 A resolution. Compared with the previous structure of the two domains in conjunction with winged-helix modules 3 and 4, the first winged-helix domain underwent a substantial conformational change during which the alpha-helical and beta-sheet portions of the element opened up like a shell. This conformational rearrangement was elicited by a change in the orientation of Trp396, leading to the disclosure of a bona fide ligand-binding site in the direct vicinity of Trp396. Additionally, the C-terminal tail of the second domain followed a different path compared with the previous structure. It is conceivable that these conformational switches constitute part of the molecular mechanism that underlies the communication between the N-terminal part of SelB, which binds Sec-tRNA(Sec) and GTP, and the C-terminal part of the protein, which binds selenocysteine-insertion sequences.
Ganichkin
Oleg
O
Max-Planck-Institut für Biophysikalische Chemie, Makromolekulare Röntgenkristallographie, Am Fassberg 11, D-37077 Göttingen, Germany.
Wahl
Markus C
MC
D020816:Amino Acid Motifs; D001419:Bacteria / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry*; D001665:Binding Sites; D003001:Cloning, Molecular; D018360:Crystallography, X-Ray / Q000379:methods; D008024:Ligands; D008958:Models, Molecular; D008968:Molecular Conformation; D010455:Peptides / Q000737:chemistry; D011487:Protein Conformation; D017510:Protein Folding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D017279:Selenocysteine / Q000737:chemistry
D001426:Bacterial Proteins; D008024:Ligands; D010455:Peptides; C061878:SelB protein, Bacteria; D017279:Selenocysteine