Adenylyl cyclases from Plasmodium, Paramecium and Tetrahymena are novel ion channel/enzyme fusion proteins.
In Paramecium, cAMP formation is stimulated by a potassium conductance, which is an intrinsic property of the adenylyl cyclase. We cloned a full-length cDNA and several gDNA fragments from Paramecium and Tetrahymena coding for adenylyl cyclases with a novel domain composition. A putative N-terminal ion channel domain contains a canonical S4 voltage-sensor and a canonical potassium pore-loop located C-terminally after the last transmembrane span on the cytoplasmic side. The adenylyl cyclase catalyst is C-terminally located. DNA microinjection of a green fluorescent protein (GFP)-tagged construct into the macronucleus of Paramecium resulted in ciliary localization of the expressed protein. An identical gene coding for an ion-channel adenylyl cyclase was cloned from the malaria parasite Plasmodium falciparum. Expression of the catalytic domain of the latter in Sf9 cells yielded an active homodimeric adenylyl cyclase. The occurrence of this highly unique subtype of adenylyl cyclase appears to be restricted to ciliates and apicomplexa.
Weber
Jost H
JH
Abteilung Pharmazeutische Biochemie, Fakultät für Chemie und Pharmazie, Universität Tübingen, Morgenstelle 8, 72076 Tübingen, Germany.
Vishnyakov
Andrey
A
Hambach
Kristina
K
Schultz
Anita
A
Schultz
Joachim E
JE
Linder
Jürgen U
JU
D000262:Adenylyl Cyclases / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D000595:Amino Acid Sequence / Q000235:genetics; D000818:Animals; D001483:Base Sequence / Q000235:genetics; D002923:Cilia / Q000235:genetics / Q000378:metabolism; D000242:Cyclic AMP / Q000096:biosynthesis; D018076:DNA, Complementary / Q000032:analysis / Q000235:genetics; D015971:Gene Expression Regulation, Enzymologic / Q000235:genetics; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins; D008969:Molecular Sequence Data; D010247:Paramecium / Q000201:enzymology* / Q000235:genetics; D010963:Plasmodium falciparum / Q000201:enzymology* / Q000235:genetics; D011188:Potassium / Q000378:metabolism; D015221:Potassium Channels / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D020033:Protein Isoforms / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D017434:Protein Structure, Tertiary / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D013768:Tetrahymena / Q000201:enzymology* / Q000235:genetics
D018076:DNA, Complementary; D008164:Luminescent Proteins; D015221:Potassium Channels; D020033:Protein Isoforms; D049452:Green Fluorescent Proteins; D000242:Cyclic AMP; D000262:Adenylyl Cyclases; D011188:Potassium