A Novel Negative Fe-Deficiency-Responsive Element and a TGGCA-Type-Like FeRE Control the Expression of FTR1 in Chlamydomonas reinhardtii

Figure 4

Scanning mutagenesis analysis of the FTR1 −319/−292 region. A series of nucleotide substitutions were introduced into the −319/−292 region. The changed nucleotides are underlined. The conservation sequence of FtrFeRE3 is highlighted in red. The Ars activities (nmol p-nitrophenol × min−1 × 10−6 cells) expressed from constructs were measured under –Fe (0𝜇M) or +Fe(18𝜇M) conditions. Black and white circles represent the Ars activities in independent transformants under −Fe or +Fe conditions, respectively. Bars indicate the median values. N represents the number of the transformants examined for the activity. The cotransformation frequency of the constructs was detected by PCR with 16 Arg independent transformants tested in each line.