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Publication Abstract from PubMed

Selenocysteine (Sec) is the "21st" amino acid and is genetically encoded by an unusual incorporation system. The stop codon UGA becomes a Sec codon when the selenocysteine insertion sequence (SECIS) exists downstream of UGA. Sec incorporation requires a specific elongation factor, SelB, which recognizes tRNA(Sec) via use of an EF-Tu-like domain and the SECIS mRNA hairpin via use of a C-terminal domain (SelB-C). SelB functions in multiple translational steps: binding to SECIS mRNA and tRNA(Sec), delivery of tRNA(Sec) onto an A site, GTP hydrolysis, and release from tRNA and mRNA. However, this dynamic mechanism remains to be revealed. Here, we report a large domain rearrangement in the structure of SelB-C complexed with RNA. Surprisingly, the interdomain region forms new interactions with the phosphate backbone of a neighboring RNA, distinct from SECIS RNA binding. This SelB-RNA interaction is sequence independent, possibly reflecting SelB-tRNA/-rRNA recognitions. Based on these data, the dynamic SelB-ribosome-mRNA-tRNA interactions will be discussed.

Structural basis for dynamic interdomain movement and RNA recognition of the selenocysteine-specific elongation factor SelB.,Ose T, Soler N, Rasubala L, Kuroki K, Kohda D, Fourmy D, Yoshizawa S, Maenaka K Structure. 2007 May;15(5):577-86. PMID:17502103^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.