文档介绍：e EF-G and EF-Tu Structures and
Translation Elongation in Bacteria
Poul Nissen and Jens
University of Aarhus, Aarhus, Denmark
The elongation cycle is the productive phase of protein 50S subunit, which reacts by inducing hydrolysis of GTP
biosynthesis. The ic message in mRNA is a working on EF-Tu at the GTPase center of the ribosome. EF-Tu in
transcript of a gene on DNA and it is translated one triplet its GDP form undergoes a large conformational change
codon at a time during this phase. Thereby, a specific amino and is released from the plex and from the
acid sequence is synthesized and the final product represents a ribosome. The universal A end of tRNA is then
functional protein of the living cell. The translation is free to swing into the peptidyl transferase center of the
performed on the ribosome, which is a plex of 50S subunit, where the formation of a new peptide bond
ribosomal RNA and ribosomal proteins. The ribosome is between the growing polypeptide and the ing
organized into two subunits, the large 50S subunit and the amino acid is performed with the help of catalytic
small 30S subunit. tRNA molecules provide amino acids for residues of the ribosomal RNA. The released
the protein biosynthesis and they are activated by the EF-Tu:GDP is reactivated to EF-Tu:GTP with the help
attachment to tRNA by an aminoacyl bond. During the of the nucleotide exchange factor EF-Ts.
elongation phase the ribosome is assisted by three elongation After peptidyl transfer the nascent polypeptide chain
factors: (1) elongation factor Tu (EF-Tu), which brings to the is attached to the ing tRNA, with its anticodon
ribosome amino-acylated tRNAs (aa-tRNAs) for decoding at still at the A site of the 30S subunit. It must be shifted to
the 30S subunit, (2) elongation factor G (EF-G), which assists the P site together with the mRNA by exactly one codon.
the ribosome in translocating mRNA and tRNAs, and (3) This is performed by EF-G in the translocation stage of
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