The detection of natural opal suppressor seryl‐tRNA in Escherichia coli by the dot blot hybridization and its phosphorylation by a tRNA kinase

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Abstract
It was believed that there was no natural suppressor tRNA in Escherichia coli, however, it has been suggested that selC, relating to the synthesis of formate dehydrogenase of a selenoprotein [(1988) Nature 331, 723–725], codes for tRNA, even though the presence of tRNA has not yet been demonstrated. We detected the product of selC in the tRNA preparation of the E. coli MC 4100 strain by the dot blot hybridization method with a DNA probe (ACCGCTGGCGGC) corresponding to the extra arm of selC tRNA. Two hybridization peaks were found in the chromatographic pattern from Sephadex A50. The amount of tRNA was estimated to be about 0.03% of the total tRNA. The suppressor [3H]seryl-tRNA was phosphorylated by a tRNA kinase in E. coli B. These results suggest that the opal suppressor seryl-tRNA in E. coli should be converted to selenocysteyl-tRNA through phosphoseryl-tRNA, and occurs in vertebrates as a general phenomenon.