Isolation and functional analysis of a strong specific promoter in photosynthetic tissues

PNZIP gene promoter has been cloned from Pharbitis nil by adaptor PCR, which conforms to eukaryotic promoter characteristic. Primer extension analysis showed that the transcription start site was located 122 nucleotides upstream of the translation start site of PNZIP gene. According to the characteristic of PNZIP promoter, a series of deletions were purposely made by PCR. Five deletion fragments were fused to upstream of GUS gene and transferred into tobacco. Fluorometric GUS assay showed that five different length promoters all could specifically drive GUS gene expression in photosynthetic tissues and their activities decreased along with the gradual deletion of PNZIP promoter. In addition, the activity of full-length promoter was 9 times higher than that of CaMV 35S in leaf. PNZIP promoter may have two putative cis-elements, GAAATA and GATACT, which relate to gene expression in photosynthetic tissues. GATACT may determine the gene specific expression in photosynthetic tissues, while GAAATA, perhaps, as an enhancer, increases the intensity of gene expression.