Constitutive glucose-induced activation of the Ras-cAMP pathway and aberrant stationary-phase entry on a glucose-containing medium in the Saccharomyces cerevisiae glucose-repression mutant hex2
Summary: Addition of glucose to cells of the yeast Saccharomyces cerevisiae growing on a nonfermentable carbon source triggers a rapid, transient increase in the cAMP level. The occurrence of this cAMP spike appears to be correlated inversely with the glucose-repression state of the cells. This was also observed for the hex2 mutant, which is deficient in glucose repression and which displayed the cAMP signal constitutively. When cells of the hex2 mutant were starved for nitrogen on a glucose-containing medium, they rapidly lost viability, similarly to mutants with overactivation of the Ras-adenylate cyclase pathway. Flow cytometry measurements showed that G1 arrest of the hex2 mutant under such conditions was incomplete. Trehalose accumulation, a typical feature of cells entering the stationary phase G0, was very short-lived in the hex2 mutant under the same conditions. These results are in agreement with the presence of continuous glucose-triggered activation of cAMP synthesis in hex2 cells on a glucose-containing nitrogen-starvation medium. In the course of these experiments a spontaneous suppressor mutant, shx (for suppressor of hex2), was isolated which survived nitrogen starvation on a glucose-containing medium much better than the hex2 strain. It also showed normal G1 arrest and much longer accumulation of trehalose. The suppressor mutation also caused inability to grow on nonfermentable carbon sources and absence of invertase derepression, and it was epistatic to hex2 for these characteristics also. The isolation of this epistatic derepression mutation supports the idea that the defect in glucose repression of the hex2 mutant is the cause of its rapid loss of viability during nitrogen starvation on a glucose-containing medium. Substitution of glucose for glycerol partially abolished the rapid loss of viability in the hex2 mutant. These results suggest that the glucose-repressible character of the pathway involved in glucose-triggered activation of cAMP synthesis might have a physiological role in preventing overstimulation of cAMP synthesis and allowing proper entrance into the stationary-phase G0 in a medium containing ample glucose but lacking another essential nutrient for growth. Such a situation might be quite common in the glucose-rich natural environment of S. cerevisiae.
ArgμellesJ.C.,
MbonyiK.,
Van AelstL,
VanhalewynM.,
JansA.W.H.,
TheveleinJ.M.1990; Absence of glucose-induced cAMP signaling in theSaccharomjces cerevisiae mutantscat1 andcat3which are deficient in derepression of glucose-repressible proteins.. Arch Microbiol 154:199–205
BelazziT.,
WagnerA.,
WieserR.,
SchanzM.,
AdamG.,
HartigA.,
RuisH.1991; Negative regulation of transcription of theSaccharomjces cerevisiae catalase T(CTT1) gene by cAMP is mediated by a positive control element.. EMBO J 10:585–592
BeullensM.,
MbonyiK.,
GeertsL,
GladinesD.,
DetremerieK.,
JansA.W.H.,
TheveleinJ.M.1988; Studies on the mechanism of the glucose-induced cAMP-signal in glycolysis- and glucose repression-mutants of the yeastSaccharomjces cerevisiae.
. Eur J Biochem 172:227–231
BissingerP.H.,
WieserR.,
HamiltonB.,
RuisH.1989; Control ofSaccharomjces cerevisiae catalase T gene(CTT1) expression by nutrient supply via the RAS-cyclic AMP pathway.. Mol Cell Biol 9:1309–1315
DurnezP.,
PernambucoM.B.,
OrisE.,
ArgUellesJ.-C.,
MergelsbergH.,
TheveleinJ.M.1994; Activation of trehalase during growth induction by nitrogen sources in the yeastSaccharomjces cerevisiae depends on the free catalytic subunits of cAMP-dependent protein kinase.. Yeast 10:1049–1064
FlickJ. S.,
JohnstonM.1991; GRR1 ofSaccharomjces cerevisiaeis required for glucose repression and encodes a protein with leucine-rich repeats.. Mol Cell Biol 11:5101–5112
HirimburegamaK.,
DurnezP.,
KelemanJ.,
OrisE.,
VergauwenR.,
MergelsbergH.,
TheveleinJ.M.1992; Nutrient-induced activation of trehalase in nutrient-starved cells of the yeastSaccharomjces cerevisiae. cAMP is not involved as second messenger.. J Gen Microbiol 138:2035–2043
JohnstonM.,
CarlsonM.1992; Regulation of carbon and phosphate utilization.. In The Molecular and Cellular Biology of the Yeast Saccharomjces,Gene Expression, 2: pp. 193–281JonesE. W.,
Pringle J. R.,
Broach.J.R.
Edited by Cold Spring Harbor, NY:: Cold Spring Harbor Laboratory.;
MatsumotoK.,
UnoI.,
IshikawaT.1983; Control of cell division inSaccharomjces cerevisiae mutants defective in adenylate cyclase and cAMP-dependent protein kinase.. Exp Cell Res 146:151–161
MbonyiK.,
BeullensM.,
DetremerieK.,
GeertsL.,
TheveleinJ.M.1988; Requirement of one functionalRAS gene and inability of an oncogenic ras-variant to mediate the glucose-induced cAMP signal in the yeastSaccharomjces cerevisiae.
. Mol Cell Biol 8:3051–3057
MountainH.A.,
SudberyP.E.1990; The relationship of growth rate and catabolite repression withWHI2 expression and cell size inSaccharomjces cerevisiae.
. J Gen Microbiol 136:733–737
NevesM.J.,
JorgeJ.A.,
FrancoisJ.M.,
TerenziH.F.1991; Effects of heat shock on the level of trehalose and glycogen, and on the induction of thermotolerance inNeurospora crassa.
. FEBS Lett 283:19–22
NiederacherD.,
EntianK.D.1991; Characterization of Hex2 protein, a negative regulatory element necessary for glucose repression in yeast.. Eur J Biochem 200:311–319
TanakaK.,
NakafukuM.,
TamanoiF.,
KaziroY.,
MatsumotoK.,
Toh-eA.1990; IRA2, a second gene ofSaccharomyces cerevisiaethat encodes a protein with a domain homologous to mammalian Ras GTPase-activating protein.. Mol Cell Biol 10:4303–4313
TatchellK.1993; RAS genes in the budding yeast Saccbaromyces cerevisiae.
. In Signal Transduction. Prokayotic and Simple Eukayotzc Systems pp. 147–188KurjanJ.,
Taylor.B. L.
Edited by San Diego:: Academic Press;
TheveleinJ.M.1991; Fermentable sugars and intracellular acidification as specific activators of the RAS-adenylate cyclase signalling pathway in yeast: the relationship to nutrient-induced cell cycle control.. Mol Microbiol 5:1301–1307
TheveleinJ.M.,
BeullensM.1985; Cyclic AMP and the stimulation of trehalase activity in the yeastSaccharomyces cerevisiaeby carbon sources, nitrogen sources and inhibitors of protein synthesis.. J Gen Microbiol 131:3199–3209
TheveleinJ.M.,
BeullensM.,
HonshovenF.,
HoebeeckG.,
DetremerieK.,
Den HollanderJ.A.,
JansA.W.H.1987; Regulation of the cAMP level in the yeastSaccharomyces cerevisiae:intracellular pH and the effect of membrane depolarizing compounds.. J Gen Microbiol 133:2191–2196
TodaT.,
CameronS.,
SassP.,
ZollerM.,
ScottJ.D.,
McBullenB.,
HurwitzM.,
KrebsE.G.,
WiglerM.1987a; Cloning and characterization ofBCY1, a locus encoding a regulatory subunit of the cyclic AMP-dependent protein kinase inSaccharomyces cerevisiae.
. Mol Cell Biol 7:1371–1377
TodaT.,
CameronS.,
SassP.,
ZollerM.,
WiglerM.1987b; Three different genes inSaccharomyces cerevisiae encode the catalytic subunits of the cAMP-dependent protein kinase.. Cell 50:277–287
Constitutive glucose-induced activation of the Ras-cAMP pathway and aberrant stationary-phase entry on a glucose-containing medium in the Saccharomyces cerevisiae glucose-repression mutant hex2