Effects of calmodulin on DNA-binding activity of heat shock transcription factor in vitro

The DNA-binding activity of heat shocktranscription factor (HSF) was induced by heat shock (HS) of a whole cell extract. Addition of antiserum, specific toCaM, to a whole cell extract reduced bind of the HSF to the heat shock element (HSE) with maize, and the re-addition of CaM to the sample restored the activity of the HSF forbinding to HSE. In addition, DNA-binding activity of the HSF was also induced by directly adding CaM to a whole cell extract at non-HS temperature with maize. Similar resultswere obtained with wheat and tomato. Our observationprovide the first example of the involvement of CaM inregulation of the DNA-binding activity of the HSF.