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A mutation in Saccharomyces cerevisiae adenylate cyclase, Cyr1 K1876M , specifically affects glucose‐ and acidification‐induced cAMP signalling and not the basal cAMP level
Author(s) -
Vanhalewyn Mieke,
Dumortier Françoise,
Debast Gilda,
Colombo Sonia,
Ma Pingsheng,
Winderickx Joris,
Van Dijck Patrick,
Thevelein Johan M.
Publication year - 1999
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1046/j.1365-2958.1999.01479.x
Subject(s) - biology , adenylate kinase , saccharomyces cerevisiae , cyclase , basal (medicine) , signalling , mutant , mutation , biochemistry , microbiology and biotechnology , genetics , endocrinology , yeast , enzyme , gene , insulin
In the yeast Saccharomyces cerevisiae , the addition of glucose to derepressed cells and intracellular acidification trigger a rapid increase in the cAMP level within 1 min. We have identified a mutation in the genetic background of several related ‘wild‐type’ laboratory yeast strains (e.g. ENY.cat80‐7A, CEN.PK2‐1C) that largely prevents both cAMP responses, and we have called it lcr1 (for l ack of c AMP r esponses). Subsequent analysis showed that lcr1 was allelic to CYR1/CDC35 , encoding adenylate cyclase, and that it contained an A to T substitution at position 5627. This corresponds to a K1876M substitution near the end of the catalytic domain in adenylate cyclase. Introduction of the A5627T mutation into the CYR1 gene of a W303‐1A wild‐type strain largely eliminated glucose‐ and acidification‐induced cAMP signalling and also the transient cAMP increase that occurs in the lag phase of growth. Hence, lysine 1876 of adenylate cyclase is essential for cAMP responses in vivo . Lysine 1876 is conserved in Schizosaccharomyces pombe adenylate cyclase. Mn 2+ ‐dependent adenylate cyclase activity in isolated plasma membranes of the cyr1 met1876 ( lcr1 ) strain was similar to that in the isogenic wild‐type strain, but GTP/Mg 2+ ‐dependent activity was strongly reduced, consistent with the absence of signalling through adenylate cyclase in vivo . Glucose‐induced activation of trehalase was reduced and mobilization of trehalose and glycogen and loss of stress resistance were delayed in the cyr1 met1876 ( lcr1 ) mutant. During exponential growth on glucose, there was little effect on these protein kinase A (PKA) targets, indicating that the importance of glucose‐induced cAMP signalling is restricted to the transition from gluconeogenic/respiratory to fermentative growth. Inhibition of growth by weak acids was reduced, consistent with prevention of the intracellular acidification effect on cAMP by the cyr1 met1876 ( lcr1 ) mutation. The mutation partially suppressed the effect of RAS2 val19 and GPA2 val132 on several PKA targets. These results demonstrate the usefulness of the cyr1 met1876 ( lcr1 ) mutation for epistasis studies on the signalling function of the cAMP pathway.