The nucleotide sequence of the rho gene of E. coli K-12.

We have determined the nucleotide sequence of the rho gene which encodes the E. coli K-12 transcription termination factor. The structural gene was located on a cloned 3.6 kilobase BglII-HindIII restriction fragment by the introduction of the insertion element gamma delta and analysis of the recombinant plasmids by restriction analysis and in maxicells. The coding region consists of 1260 nucleotides directing the synthesis of a polypeptide 419 amino acids in length with a calculated molecular weight of 46,094. The deduced amino acid composition, amino-terminal protein sequence and calculated molecular weight are consistent with the data from the analysis of purified rho protein (16). We have shown that the rho genes from E. coli K-12, B and C strains are located on PvuII-HindIII fragments of the same size by hybridization to the rho (K-12) coding sequences.