Evolutionary dynamics of tryptophan tRNAs in Mycoplasma capricolum.
Mycoplasma capricolum uses two tryptophan codons, the "universal" nonsense codon UGA and the universal codon UGG. The bacterium contains two tryptophan tRNAs, one with anticodon UCA, (U: 2'-O-methyl U derivative), and the other with CCA (5'-C: partially 2'-O-methylated). tRNAUCA would translate codons UGA and probably UGG by wobbling. tRNACCA is much less charged by tryptophan in the cells than tRNAUCA, and the intracellular amount of tRNACCA is 5-10 times lower than that of tRNAUCA. The genes for these two tRNAs are separated by a terminator-like structure in a single operon. In vitro transcription experiments suggest that the predominance of tRNAUCA over tRNACCA results from the attenuation of transcription by this terminator-like structure.
Yamao
F
F
Department of Biology, Faculty of Science, Nagoya University, Japan.
Iwagami
S
S
Azumi
Y
Y
Muto
A
A
Osawa
S
S
Fujita
N
N
Ishihama
A
A
D001483:Base Sequence; D005075:Biological Evolution; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism; D005786:Gene Expression Regulation; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D009174:Mycoplasma / Q000235:genetics*; D009690:Nucleic Acid Conformation; D010957:Plasmids; D012345:RNA, Transfer, Amino Acid-Specific / Q000235:genetics*; D012364:RNA, Transfer, Trp / Q000235:genetics*; D014158:Transcription, Genetic
D012345:RNA, Transfer, Amino Acid-Specific; D012364:RNA, Transfer, Trp; D012321:DNA-Directed RNA Polymerases