Bacillus subtilis tRNA Pro with the anticodon mo 5UGG can recognize the codon CCC

Abstract

In Bacillus subtilis, four codons, CCU, CCC, CCA, and CCG, are used for proline. There exists, however, only one proline-specific tRNA having the anticodon mo 5UGG. Here, we found that this tRNA Pro(mo 5UGG) can read not only the codons CCA, CCG and CCU but also CCC, using an in vitro assay system. This means that the first nucleoside of its anticodon, 5-methoxyuridine (mo 5U), recognizes A, G, U and C. On the other hand, it was reported that mo 5U at the first position of the anticodon of tRNA Val(mo 5UAC) can recognize A, G, and U but not C. A comparison of the structure of the anticodon stem and loop of tRNA Pro(mo 5UGG) with those of other tRNAs containing mo 5U at the first positions of the anticodons suggests that a modification of nucleoside 32 to pseudouridine (Ψ) enables tRNA Pro(mo 5UGG) to read the CCC codon.