Importance of formylability and anticodon stem sequence to give a tRNA(Met) an initiator identity in Escherichia coli.
AUTOR(ES)
Guillon, J M
RESUMO
In bacteria, the free amino group of the methionylated initiator tRNA is specifically modified by the addition of a formyl group. The functional relevance of such a formylation for the initiation of translation is not yet precisely understood. Advantage was taken here of the availability of the fmt gene, encoding the Escherichia coli Met-tRNA(fMet) formyltransferase, to measure the influence of variations in the level of formyltransferase activity on the involvement of various mutant tRNA(fMet) and tRNA(mMet) species in either initiation or elongation in vivo. The data obtained established that formylation plays a dual role, firstly, by dictating tRNA(fMet) to engage in the initiation of translation, and secondly, by preventing the misappropriation of this tRNA by the elongation apparatus. The importance of formylation in the initiator identity of tRNA(fMet) was further shown by the demonstration that elongator tRNA(fMet) may be used in initiation and no longer in elongation, provided that it is mutated into a formylatable species and is given the three G.C base pairs characteristic of the anticodon stem of initiator tRNAs.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=204892Documentos Relacionados
- The primary structure of cytoplasmic initiator tRNA(Met) from Schizosaccharomyces pombe.
- Nucleotide sequence of Chlamydomonas reinhardtii mitochondrial genes coding for tRNA(Gln) (UUG) and tRNA(Met) (CAU).
- An anticodon sequence mutant of Escherichia coli initiator tRNA: possible importance of a newly acquired base modification next to the anticodon on its activity in initiation.
- Specific binding of tRNAMet to 23S rRNA of Escherichia coli.
- Escherichia coli formylmethionine tRNA: mutations in GGGCCC sequence conserved in anticodon stem of initiator tRNAs affect initiation of protein synthesis and conformation of anticodon loop.
