Cloning and characterization of the gene for Escherichia coli tryptophanyl-transfer ribonucleic acid synthetase.

From a Clark-Carbon plasmid containing trpS, the structural gene for the tryptophanyl-transfer ribonucleic acid synthetase of Escherichia coli, we subcloned a 2.6-kilobase fragment that has trpS and its neighboring regions. The location and orientation of trpS in the deoxyribonucleic acid insert was determined by deoxyribonucleic acid sequencing. In vitro transcription experiments and S1 nuclease mapping studies with in vivo message established that transcription is initiated at the same site in vivo and in vitro, approximately 58 base pairs upstream from the trpS coding region. We also describe the construction of an inphase trpS-lacZ gene fusion that is under the control of the trpS promoter and encodes a hybrid protein with beta-galactosidase activity.