GTP gamma S regulation of a 12-transmembrane guanylyl cyclase is retained after mutation to an adenylyl cyclase

Citation
J. Roelofs et al., GTP gamma S regulation of a 12-transmembrane guanylyl cyclase is retained after mutation to an adenylyl cyclase, J BIOL CHEM, 276(44), 2001, pp. 40740-40745
Citations number
62
Categorie Soggetti
Biochemistry & Biophysics
Journal title
JOURNAL OF BIOLOGICAL CHEMISTRY
ISSN journal
00219258 → ACNP
Volume
276
Issue
44
Year of publication
2001
Pages
40740 - 40745
Database
ISI
SICI code
0021-9258(20011102)276:44<40740:GGSROA>2.0.ZU;2-R
Abstract
DdGCA is a Dictyostelium guanylyl cyclase with a topology typical for mamma lian adenylyl cyclases containing 12 transmembrane-spanning regions and two cyclase domain. In Dictyostelium cells heterotrimeric G-proteins are essen tial for guanylyl cyclase activation by extracellular cAMP. In lysates, gua nylyl cyclase activity is strongly stimulated by guanosine 5'-3-O-(thio) tr iphosphate (GTP gammaS), which is also a substrate of the enzyme. DdGCA was converted to an adenylyl cyclase by introducing three point mutations. Exp ression of the obtained DdGCA(kqd) in adenylyl cyclase-defective cells rest ored the phenotype of the mutant. GTP gammaS stimulated the adenylyl cyclas e activity of DdGCAkqd with properties similar to those of the wild-type en zyme (decrease of K-m and increase of V-max), demonstrating that GTP gammaS stimulation is independent of substrate specificity. Furthermore, GTP gamm aS activation of DdGCAkqd is retained in several null mutants of Ga and G b eta proteins, indicating that GTP gammaS activation is not mediated by a he terotrimerie G-protein but possibly by a monomeric G-protein.