Determination of the initiation sites of transcription and translation of the uvrD gene of Escherichia coli.

Prior to the analysis of transcription and translation, the nucleotide sequence of the uvrD gene and its neighboring regions was determined by the method of Maxam and Gilbert (Maxam & Gilbert (1980) Methods Enzymol. 65, 499-560). Disagreement in 14 positions between the nucleotide sequence determined by us and that reported previously (Finch & Emmerson (1984) Nucl. Acids Res. 11, 5789-5799) was found. We reexamined these disputed regions. The initiation site of transcription of the uvrD gene was determined by analyzing the transcripts synthesized in vitro. It was found that transcription of the uvrD gene starts from the A nucleotide, which is the first one of the SOS box of the uvrD. The amino terminal sequence and the amino acid composition of the purified UvrD protein (helicase II) were determined. It was found that translation starts from the first ATG codon, which lies 77 nucleotides downstream from the initiation site of transcription. The amino acid composition of the purified UvrD protein agreed well with that deduced from the nucleotide sequence.