A synthetic translation-terminator gene: A tool for dissecting the translation direction of a gene

Abstract A 41-nucleotide-long duplex DNA, which contains the translation termination codon TAA in six reading frames and lactose operator sequence of Escherichia coli , has been synthesized. This fragment may be useful not only for producing a truncated protein encoded in a plasmid, but also for the identification of the precise coding region and translation direction of a bacterial gene in the cloned chromosomal segment. The synthetic fragment was inserted into s-lactamase structural gene in pBR322 in order to test the in vivo activity. The plasmid produced mutant s-lactamase reduced in size, as expected from the insertion site, and rendered the host bacterium constitutive for s-galactosidase. Thus, termination codons and lactose operator in synthetic nucleotide appear to be functional in vivo.