Accurate transcription and processing of 19 Euglena chloroplast tRNAs in a Euglena soluble extract

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Abstract
The transcription and accurate processing of 19 different Euglena gracilis chloroplast tRNAs in a homologous chloroplast soluble extract is described. The chloroplast DNA dependent-RNA polymerase present in the extract selectively transcribes the tRNA genes (Greenberg et al., 1984, J. Biol. Chem., 259: 14880–14887). Two dimensional polyacrylamide gel electrophoresis and RNA fingerprint analysis were used to show that the tRNAs are correctly processed at the 5′- and 3′-ends. The Euglena chloroplast soluble extract contains a 5′-processing or ‘RNase P-like’ activity and RNases responsible for processing tRNA termini. However, it was not determined if the 3′-CCA was added. Therefore, the soluble extract contains activities that are quite similar to an extract of spinach chloroplasts (Greenberg et al. (1984), Plant Mol. Biol., 3: 97–109). After transcription of total chloroplast DNA in the Euglena soluble extract, thirty-three tRNA sized products were resolved by two dimensional polyacrylamide gel electrophoresis. Nineteen tRNAs could be identified in this mixture.