E. Boy-marcotte et al., The heat shock response in yeast: differential regulations and contributions of the Msn2p/Msn4p and Hsf1p regulons, MOL MICROB, 33(2), 1999, pp. 274-283
The heat shock transcription factor Hsf1p and the stress-responsive transcr
iption factors Msn2p and Msn4p are activated by heat shock in the yeast Sac
charomyces cerevisiae. Their respective contributions to heat shock protein
induction have been analysed by comparison of mutants and wild-type strain
s using [S-35]-methionine labelling and two-dimensional gel electrophoresis
. Among 52 proteins induced by a shift from 25 degrees C to 38 degrees C, h
alf of them were found to be dependent upon Msn2p and/or Msn4p (including m
ostly antioxidants and enzymes involved in carbon metabolism), while the ot
her half (including mostly chaperones and associated proteins) were depende
nt upon Hsf1p. The two sets of proteins overlapped only slightly. Three pro
teins were induced independently of these transcription factors, suggesting
the involvement of other transcription factor(s). The Ras/cAMP/PKA signall
ing pathway cAMP had a negative effect on the induction of the Msn2p/Msn4p
regulon, but did not affect the Hsf1p regulon, Thus, the two types of trans
cription factor are regulated differently and control two sets of functiona
lly distinct proteins, suggesting two different physiological roles in the
heat shock cellular response.