Figure 1.

The psaA 5′ UTR confers a PsaB-dependent expression to the reporter gene aadA. (A) Schematic map of the petA-petD chloroplast region where the 5′psaA-aadA chimeric gene has been inserted, in direct orientation with respect to the petA gene, at the neutral EcoRV site (V). ↱ indicates transcription start sites. (B) Growth of independent transformants, derived from the recipient strains listed in the left, in the presence of increasing concentrations of antibiotics. The PsaA_Tr and maa-F31 strains are devoid of PsaA expression (see later). (C) Accumulation of the chimeric aadA (and petA, as a loading control) mRNAs in the wild-type strain and in some of the transformants presented in panel B.