MSN2P AND MSN4P CONTROL A LARGE NUMBER OF GENES INDUCED AT THE DIAUXIC TRANSITION WHICH ARE REPRESSED BY CYCLIC-AMP IN SACCHAROMYCES-CEREVISIAE

The multicopy suppressors of the snf1 defect, Msn2p and Msn4p transcri ption factors (Msn2/4p), activate genes through the stress-responsive cis element (CCCCT) in response to various stresses, This cis element is also the target for repression by the cyclic AMP (cAMP)-signaling p athway. We analyzed the two-dimensional gel electrophoresis pattern of protein synthesis of the msn2 msn4 double mutant and compared it with that of the wild-type strain during exponential growth phase and at t he diauxic transition, Thirty-nine gene products (including those of A LD3, GDH3, GLK1, GPP2, HSP104 HXK1, PGM2, SOD2, SSA3, SSA4, TKL2, TPS1 , and YBR149W) are dependent upon Msn2/4p for their induction at the d iauxic transition, The expression of all these genes is repressed by c AMP, Thirty other genes identified during this study are still inducib le in the mutant, A subset of these genes were found to be superinduce d at the diauxic transition, and others were subject to cAMP repressio n (including ACH1, ADH2, ALD6, ATP2, GPD1, ICL1, and KGD2), We conclud e from this analysis that Msn2/4p control a large number of genes indu ced at the diauxic transition but that other, as-yet-uncharacterized r egulators, also contribute to this response, In addition, we show here that cAMP repression applies to both Msn2/4p-dependent and -independe nt control of gene Expression at the diauxic shift, Furthermore, the T act that ail the Msn2/4p gene targets are subject to cAMP repression s uggests that these regulators could be targets far the cAMP-signaling pathway.