Figure 1.

Construction of the plasmid vectors expressing the deleted NR proteins ΔA-NR and ΔS-NR. We first amplified by PCR a 198-bp fragment containing the ΔA deletion and a 110-bp fragment containing the ΔS deletion using, respectively, the primers 26 and 27 or the primers 26 and 28 (A). The amplified fragments called, respectively, megaprimers ΔA and ΔS, were then used as primers for a second PCR with primer 6 (B). The resulting DNA fragments were cloned between the SstI and Spel sites of the plasmid pBluescript (C). These new plasmids were digested by SpeI and PstI and an SpeI–PstI fragment was then introduced downstream of the deleted sequence to recover the complete NR-coding sequence (D). These constructs were called pΔA-NR and pΔS-NR. The dark bars represent the NR-coding sequence. S, SstI; Sp, SpeI; P, PstI.