A 5′ flaking nucleotide sequence of 1,101 bp of rice catalase-B gene (
CatB) coding sequence having coordinates from −808 to +294 with respect to the transcription start site was transcriptionally
fused to the β-glucuronidase gene (GUS), and functionally analyzed through transient and stable expression assay systems to
identify the minimal promoter sequence containing the important
cis-regulatory regions controlling its expression. The progressive up-stream and down-stream (5′/3′) deletion analysis of the
1,101-bp fragment revealed that minimal nucleotide sequences spanning from −121 to +56 possessed maximum GUS activity, which
was nearly six- to eightfold higher than GUS activity driven by CaMV35S promoter. DNase I footprint and gel retardation analysis
of the minimal promoter sequence with nuclear extract revealed the presence of a “AAAAG” nucleotide signature referring to
DNA-binding with one finger (Dof) transcription factor. In addition, the presence of CAAT-box sequence was also evident. The
Dof interacting sequence in
CatB promoter of rice has been established for the first time in this work.
Keywords
CatB
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cis-element - Dof - Rice - Promoter analysis