RRC ID 29035
Author Roelofs J, Van Haastert PJ.
Title Characterization of two unusual guanylyl cyclases from dictyostelium.
Journal J Biol Chem
Abstract Guanylyl cyclase A (GCA) and soluble guanylyl cyclase (sGC) encode GCs in Dictyostelium and have a topology similar to 12-transmembrane and soluble adenylyl cyclase, respectively. We demonstrate that all detectable GC activity is lost in a cell line in which both genes have been inactivated. Cell lines with one gene inactivated were used to characterize the other guanylyl cyclase (i.e. GCA in sgc(minus sign) null cells and sGC in gca(minus sign) null cells). Despite the different topologies, the enzymes have many properties in common. In vivo, extracellular cAMP activates both enzymes via a G-protein-coupled receptor. In vitro, both enzymes are activated by GTPgammaS (K(a) = 11 and 8 microm for GCA and sGC, respectively). The addition of GTPgammaS leads to a 1.5-fold increase of V(max) and a 3.5-fold increase of the affinity for GTP. Ca(2+) inhibits both GCA and sGC with K(i) of about 50 and 200 nm, respectively. Other biochemical properties are very different; GCA is expressed mainly during growth and multicellular development, whereas sGC is expressed mainly during cell aggregation. Folic acid and cAMP activate GCA maximally about 2.5-fold, whereas sGC is activated about 8-fold. Osmotic stress strongly stimulates sGC but has no effect on GCA activity. Finally, GCA is exclusively membrane-bound and is active mainly with Mg(2+), whereas sGC is predominantly soluble and more active with Mn(2+).
Volume 277(11)
Pages 9167-74
Published 2002-3-15
DOI 10.1074/jbc.M111437200
PII S0021-9258(19)36285-4
PMID 11777934
MeSH Animals Catalysis Cyclic AMP / pharmacology Cyclic GMP / physiology Dictyosteliida / enzymology* Folic Acid / pharmacology Guanosine 5'-O-(3-Thiotriphosphate) / pharmacology Guanylate Cyclase / chemistry Guanylate Cyclase / metabolism* Kinetics Magnesium / pharmacology Manganese / pharmacology Osmotic Pressure
IF 4.238
Times Cited 37
Cellular slime molds S00337