Goldman-Levi R, Kopelowitz J, Engelberg-Kulka H
Department of Molecular Biology, Hebrew University-Hadassah Medical School, Jerusalem, Israel.
DNA Res. 1994;1(3):123-7. doi: 10.1093/dnares/1.3.123.
In Escherichia coli a UGA codon can be efficiently suppressed by a suppressor tRNA(Trp) called Su9. Here, we show that the level of UGA suppression is determined by the nature of the nucleotide at the 5' side of the anticodon of the suppressor (position 33). UGA suppression occurs when a pyrimidine residue is located in position 33 of the tRNA, and suppression is more efficient with a U than with a C in this position. On the other hand, when a purine residue is located at this position UGA suppression is extremely low. These results show that in the case of tRNA Su9, the UGA codon context effect does not require base pairing between the nucleotide at the 3' side of the codon and the 5' side of the anticodon.
在大肠杆菌中，UGA密码子可被一种名为Su9的抑制性tRNA（Trp）有效抑制。在此，我们表明UGA抑制水平由抑制性tRNA反密码子5'端核苷酸的性质（第33位）决定。当嘧啶残基位于tRNA的第33位时会发生UGA抑制，且在此位置上，U比C的抑制效率更高。另一方面，当嘌呤残基位于此位置时，UGA抑制极低。这些结果表明，对于tRNA Su9而言，UGA密码子上下文效应并不需要密码子3'端核苷酸与反密码子5'端之间进行碱基配对。
