Decoding of tandem quadruplets by adjacent tRNAs with eight-base anticodon loops
AUTOR(ES)
Moore, Barry
FONTE
Oxford University Press
RESUMO
To expand the genetic code for specification of multiple non-natural amino acids, unique codons for these novel amino acids are needed. As part of a study of the potential of quadruplets as codons, the decoding of tandem UAGA quadruplets by an engineered tRNALeu with an eight-base anticodon loop, has been investigated. When GCC is the codon immediately 5′ of the first UAGA quadruplet, and release factor 1 is partially inactivated, the tandem UAGAs specify two leucines with an overall efficiency of at least 10%. The presence of a purine at anticodon loop position 32 of the tRNA decoding the codon 5′ to the first UAGA seems to influence translation of the following codon. Another finding is intraribosomal dissociation of anticodons from codons and their re-pairing to mRNA at overlapping or nearby codons. In one case where GCC is replaced by CGG, only a single Watson–Crick base pair can form upon re-pairing when decoding is resumed. This has implications for the mechanism of some cases of programmed frameshifting.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=110719Documentos Relacionados
- A cytotoxic ribonuclease which specifically cleaves four isoaccepting arginine tRNAs at their anticodon loops
- Initiator tRNAs have a unique anticodon loop conformation.
- Nucleotide sequences of two serine tRNAs with a GGA anticodon: the structure-function relationships in the serine family of E. coli tRNAs.
- Ribosomal proteins S7 and L1 are located close to the decoding site of E. coli ribosome--affinity labeling studies with modified tRNAs carrying photoreactive probes attached adjacent to the 3'-end of the anticodon.
- Nuclear-encoded mitochondrial tRNAs of Trypanosoma brucei have a modified cytidine in the anticodon loop.