Thus, when full RE is present, p73 tetramerization occurs and N-terminal domains of its DBD recruit basal transcription factors to induce transcription of the downstream gene. Yeast luciferase assay demonstrated that level of this transactivation is influenced by the spacer length within the RE. p73 activity corresponded to the expression of luciferase gene that was put under its control.
The highest transcriptional activation was observed with 0-bp spacer, suggesting the highest affinity of p73 tetramer towards it. This explains why the 0-bp spacer is found in most RE in vivo – it leads to most efficient transactivation. The 0-bp spaced RE allows the formation of p73 tetramer, which interacts with the mediator to facilitate the transcription of target genes (Figure 4a).
Notably, increasing the spacer length between half-sites of RE reduced the transactivation activity of p73, down to 10% with 1-bp spacer and further to basal level with 2-bp and 4-bp spacers. Figure 4b shows that when formation of p73 tetramer is inhibited by a longer RE spacer, basal transcription factors are not recruited.
The highest transcriptional activation was observed with 0-bp spacer, suggesting the highest affinity of p73 tetramer towards it. This explains why the 0-bp spacer is found in most RE in vivo – it leads to most efficient transactivation. The 0-bp spaced RE allows the formation of p73 tetramer, which interacts with the mediator to facilitate the transcription of target genes (Figure 4a).
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| Figure 4a: Upon its oligomerization, p73 tetramer interacts with the Mediator to recruit basal transcription factors and activate transcription |
Notably, increasing the spacer length between half-sites of RE reduced the transactivation activity of p73, down to 10% with 1-bp spacer and further to basal level with 2-bp and 4-bp spacers. Figure 4b shows that when formation of p73 tetramer is inhibited by a longer RE spacer, basal transcription factors are not recruited.
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| Figure 4b: Basal transcription are not recruited when the p73 tetramer does not form |
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