Abstract
Drosophila tissue culture cells stimulated by heat shock contain high levels of heat shock activator protein, which binds specifically to the heat-shock control DNA element. In contrast, nonshocked cells have low basal levels of binding activity. Here, we show that within 30 seconds of heat shock of intact cells the sequence-specific binding activity in whole cell extracts increases significantly, reaching a plateau by 5 min after the start of the shock; removal of the heat stimulus returns the activity to basal levels. Known chemical inducers of heat-shock genes elicit a similar pattern of specific binding activity. Moreover, this pattern is observed in the presence of protein synthesis inhibitors, even if the stimulus-withdrawal is repeated sequentially through five cycles. Our results are inconsistent with models which propose proteolysis as the chief means of mediating heat-shock transcriptional control. Rather, they suggest that heat shock activator pre-exists in normal cells in a nonbinding form, which is converted upon cell stimulus to a high affinity, sequence-specific binding form, most probably by a post-translational modification. This conversion may be crucial for the transcriptional activation of heat shock genes.
Original language | English |
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Pages (from-to) | 727-730 |
Number of pages | 4 |
Journal | Nature |
Volume | 327 |
Issue number | 6124 |
Publication status | Published - 1987 |
ASJC Scopus subject areas
- General