Promoter structure and activity of type 1 rice metallothionein-like gene

A novel stress-inducible metallothionein-like gene from rice, designated as rgMT-1 (rice genomic metallothionein-like gene-1), was isolated and sequenced. From the sequence analysis of its 5′-flanking region, two putative TATA boxes, one CAAT box, and several short sequences homologous to regulatory cis-elements previously reported were identified. Two direct repeats, one 10 bp in length (CAAAATCAAA) and the other 11 bp (GTGAAAATACT), respectively, were also found. By transient GUS (beta-glucuronidase) assay, the expression of GUS, in vitro, was enhanced by the presence of the rgMT-1 intron. The critical region which controls the basal transcription was shown to lie between -73 and -36 upstream of rgMT-1, in which one of the two putative TATA boxes was located. The promoter activity was lost completely when both putative TATA boxes were deleted. This is the first report describing the genomic structure and regulation of a monocotyledonous metal-lothionein-lLke gene critical to the response of stress.