TY - JOUR
T1 - Activating mutation of adenylyl cyclase reverses its inhibition by G proteins
AU - Zimmermann, Gregor
AU - Zhou, Dongmei
AU - Taussig, Ronald
PY - 1999
Y1 - 1999
N2 - We have implemented a yeast genetic selection developed previously by our laboratory to identify mutant mammalian type V adenylyl cyclases insensitive to inhibition by G(iα). One mutation isolated was localized to the first cytoplasmic domain at a Phe residue (position 400), which is conserved in all nine isoforms of membrane-bound mammalian adenylyl cyclase. Biochemical characterization of the F400Y mutant revealed a dramatic conversion of the G(iα) response from inhibitory to stimulatory. This mutation results in additional activating effects. The mutant exhibits an enhanced sensitivity toward activation by either G(sα) or forskolin. Synergism between G(sα) and forskolin is not observed for the F400Y mutant, presumably because the mutant already is in the sensitized state. Addition, ally, an enhancement of the basal unstimulated activity was observed. This mutation, which is the first demonstration of an activating point in a mammalian adenylyl cyclase, mimics a sensitized conformation of the wild-type enzyme that underlies the synergism between stimulatory inputs, and additionally, removes the inhibitory regulatory input provided by G(iα). Because sensitizing adenylyl cyclase toward its stimulators can have profound biological implications, this raises the possibility that naturally occurring mutations resembling those at the Phe400 residue may be associated with human disease states.
AB - We have implemented a yeast genetic selection developed previously by our laboratory to identify mutant mammalian type V adenylyl cyclases insensitive to inhibition by G(iα). One mutation isolated was localized to the first cytoplasmic domain at a Phe residue (position 400), which is conserved in all nine isoforms of membrane-bound mammalian adenylyl cyclase. Biochemical characterization of the F400Y mutant revealed a dramatic conversion of the G(iα) response from inhibitory to stimulatory. This mutation results in additional activating effects. The mutant exhibits an enhanced sensitivity toward activation by either G(sα) or forskolin. Synergism between G(sα) and forskolin is not observed for the F400Y mutant, presumably because the mutant already is in the sensitized state. Addition, ally, an enhancement of the basal unstimulated activity was observed. This mutation, which is the first demonstration of an activating point in a mammalian adenylyl cyclase, mimics a sensitized conformation of the wild-type enzyme that underlies the synergism between stimulatory inputs, and additionally, removes the inhibitory regulatory input provided by G(iα). Because sensitizing adenylyl cyclase toward its stimulators can have profound biological implications, this raises the possibility that naturally occurring mutations resembling those at the Phe400 residue may be associated with human disease states.
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U2 - 10.1124/mol.56.5.895
DO - 10.1124/mol.56.5.895
M3 - Article
C2 - 10531392
AN - SCOPUS:0032757082
SN - 0026-895X
VL - 56
SP - 895
EP - 901
JO - Molecular Pharmacology
JF - Molecular Pharmacology
IS - 5
ER -