Accurate Translocation of mRNA by the Ribosome Requires a Peptidyl Group or Its Analog on the tRNA Moving into the 30S P Site
2002; Elsevier BV; Volume: 9; Issue: 5 Linguagem: Inglês
10.1016/s1097-2765(02)00523-3
ISSN1097-4164
AutoresKurt Fredrick, Harry F. Noller,
Tópico(s)Viral Infections and Immunology Research
ResumoThe ribosome must accurately translocate mRNA to maintain the reading frame. Here, we monitor the position of mRNA within the ribosome before and after EF-G-catalyzed translocation near the initiation site. When a deacylated tRNA that is translocated to the 30S P site recognizes other nearby codons, movement of tRNA and mRNA often becomes uncoupled. Instead of moving in the 5′ direction by 3 nucleotides, the mRNA slips backward, repositioning the tRNA on an out-of-frame codon more optimally spaced from the Shine-Dalgarno sequence. In contrast, when peptidyl-tRNA or its analog (N-acetyl-aminoacyl-tRNA) is translocated in the same context, translocation of mRNA is highly accurate. If aminoacyl-tRNA is translocated, an intermediate level of translocational accuracy is observed. Thus, translocational accuracy depends on the acylation state of the tRNA entering the 30S P site.
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