tRNAf2Met Gene in the Leader Region of the nusA Operon in Escherichia coli

The promoter-proximal portion of the operon containing the Escherichia coli nusA gene has been cloned. Its nucleotide sequence shows that genes for tRNAMetf2 and a 15-kilodalton protein of unknown function precede the nusA protein gene. The sequence suggests that the three genes form a single transcription unit. Consistent with this hypothesis, purified RNA polymerase formed full-length transcripts on the cloned DNA in vitro, although transcription was frequently arrested at the intercistronic site(s) between the gene for tRNAMetf2 and the 15-kilodalton protein.