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Escherichia coli JA221 can suppress the UAG stop signal
J Lacadena1, A Martínez del Pozo, J M Mancheño
1Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas, Universidad Complutense, Madrid, Spain.
Abstract:
The Escherichia coli strain JA221 can suppress the UAG stop codon, although the existence of an amber suppressor tRNA has not previously been described for this strain. When using a plasmid to express alpha-sarcin, which has TAG as its stop signal, two proteins were obtained: a smaller protein corresponding in size to that of the expected protein, and a larger protein, which could be accounted for by the presence of a second stop codon (TGA) 18 base pairs downstream of the original. This feature of strain JA221 must therefore be considered when using this strain as a host for the production of recombinant proteins.