Regulation of T-DNA gene 7
The purpose of this study was two-fold. The first objective was to determine if Saccharomyces cerevisiae is a useful system for investigating the expression of T-DNA (it takes several months to obtain sufficient bacteria-free transformed plant tissue to investigate T-DNA transcription). A short fragment of T-DNA carrying T-DNA gene 7 was cloned into a yeast plasmid in an attempt to investigate the expression of gene 7 in yeast. The second objective was to determine the significance of a heat
... icance of a heat shock related sequence identified in the 5¹ region of T-DNA gene 7. Primer extension analysis, SI nuclease mapping, and Northern hybridizations indicate that transcription of T-DNA gene 7 in yeast is different from that of transcription of gene 7 in crown gall tumors. Transcription is different because the distance between the TATA box and the transcription initiation sites must be at least 40 nucleotides in yeast. Therefore, Saccharomyces cerevisiae does not appear to be a useful system for investigating the expression of T-DNA. Crown gall tumors were subjected to a number of stress agents, including heat shock, to determine the significance of the heat shock related sequence identified in gene 7. Primer extension analyses indicate that only cadmium and mercury have a significant effect on the expression of T-DNA gene 7. Although gene 7 responds to cadmium and mercury, the increase in transcription does not appear to be heat shock or metallothionein related, indicating that another mechanism is involved in the enhanced transcription of T-DNA gene 7 in crown gall tumors.