The pheR gene of Escherichia coli encodes tRNA(Phe), not a repressor protein.

Nucleotide sequence analysis and transposon 5 (Tn5) insertional mutagenesis indicate that the Escherichia coli gene pheR encodes tRNA(Phe) and not a repressor protein as previously reported. The coding region of pheR is identical to that of three other cloned tRNA(Phe) genes, pheU, pheV, and pheW. Multicopy plasmids carrying pheR, like those carrying pheU, pheV, or pheW, complement a temperature-sensitive lesion in the gene for the alpha-subunit of phenylalanyl-tRNA synthetase (pheS). The nucleotide sequences of the 5'-flanking DNA of pheR, pheU, and pheW are almost identical but are quite different from the same region of pheV. By comparison with pheV, which has two tandem promoters, pheR was found to have a single promoter. The expression of pheA (encoding chorismate mutase/prephenate dehydratase) in strains carrying the pheR374 allele was decreased to similar extents by multicopy plasmids containing either pheR or pheV. It is proposed that this decrease in pheA expression and the increase in expression of pheA previously reported for chromosomal pheR mutants are both mediated through the attenuation control mechanism that regulates pheA.