H. Garreau et al., Hyperphosphorylation of Msn2p and Msn4p in response to heat shock and the diauxic shift is inhibited by cAMP in Saccharomyces cerevisiae, MICROBIO-UK, 146, 2000, pp. 2113-2120
In response to various stresses, as well as during the diauxic transition,
the Msn2p and Msn4p transcription factors of Saccharomyces cerevisiae are a
ctivated and induce a large set of genes. This activation is inhibited by t
he Ras/cAMP/PKA (cAMP-dependent protein kinase) pathway. Here we show by im
munoblotting experiments that Msn2p and Msn4p are phosphorylated in vivo du
ring growth on glucose, and become hyperphosphorylated at the diauxic trans
ition and upon heat shock. This hyperphosphorylation is correlated with act
ivation of Msn2/4p-dependent transcription. An increased level of cAMP prev
ents and reverses these hyperphosphorylations. indicating that kinases othe
r than PKA are involved. These results suggest that PKA and stress-activate
d kinases control Msn2/4p activity by antagonistic phosphorylation. it was
also noted that Msn4p is transiently increased at the diauxic transition. M
sn2p and Msn4p present different hyperphosphorylation patterns in response
to different stresses.