Figure 1.

Sequences of the ndhB segment insertions in the chloroplast transformation vectors used in this study. Plasmid pRB59 contains the wild-type sequence (12) and spans an ndhB segment from −42, with respect to the 5′ editing site (site IV), to +22, with respect to the 3′ editing site (site V). Vector pRB67-Δ1 carries a deletion of a single nucleotide in the 8-nt spacer separating sites IV and V. pRB68-Δ2 has a deletion of 2 nt in the spacer, and in pRB69-i1, a single C residue was inserted into a tetracytidine motif harboring editing site IV (denoted by a lowercase C at an arbitrarily chosen position). Vector pRB73-Δ1/cm is identical to pRB67-Δ1 but carries an additional compensatory point mutation expected to restore editing at the 3′ site. See text for details. Editing sites as in the wild type are marked by vertical arrows. Deleted nucleotides are indicated by dashes, and inserted nucleotides are shown as lowercase letters. The nucleotides upstream of site IV (harboring the essential cis-acting elements for the editing of both sites in the –2/−12 region; ref. 12) are numbered in the pRB59 sequence, with editing site IV as nucleotide “0.”