title: Guanylyl cyclases with the topology of mammalian adenylyl cyclases and an N-terminal P-type ATPase-like domain in Paramecium, Tetrahymena and Plasmodium.
abstract: We cloned a guanylyl cyclase of 280 kDa from the ciliate Paramecium which has an N-terminus similar to that of a P-type ATPase and a C-terminus with a topology identical to mammalian adenylyl cyclases. Respective signature sequence motifs are conserved in both domains. The cytosolic catalytic C1a and C2a segments of the cyclase are inverted. Genes coding for topologically identical proteins with substantial sequence similarities have been cloned from Tetrahymena and were detected in sequences from Plasmodium deposited by the Malaria Genome Project. After 99 point mutations to convert the Paramecium TAA/TAG-Gln triplets to CAA/CAG, together with partial gene synthesis, the gene from Paramecium was heterologously expressed. In Sf9 cells, the holoenzyme is proteolytically processed into the two domains. Immunocytochemistry demonstrates expression of the protein in Paramecium and localizes it to cell surface membranes. The data provide a novel structural link between class III adenylyl and guanylyl cyclases and imply that the protozoan guanylyl cyclases evolved from an ancestral adenylyl cyclase independently of the mammalian guanylyl cyclase isoforms. Further, signal transmission in Ciliophora (Paramecium, Tetrahymena) and in the most important endoparasitic phylum Apicomplexa (Plasmodium) is, quite unexpectedly, closely related.
authors.affiliation: Fakultät für Chemie und Pharmazie, Universität Tübingen, Auf der Morgenstelle 8, D-72076 Tübingen, Germany.
authors.forename: J U
authors.initials: JU
authors.lastname: Linder
authors.forename: P
authors.initials: P
authors.lastname: Engel
authors.forename: A
authors.initials: A
authors.lastname: Reimer
authors.forename: T
authors.initials: T
authors.lastname: Krüger
authors.forename: H
authors.initials: H
authors.lastname: Plattner
authors.forename: A
authors.initials: A
authors.lastname: Schultz
authors.forename: J E
authors.initials: JE
authors.lastname: Schultz
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D017931:DNA Primers; D006162:Guanylate Cyclase / Q000737:chemistry* / Q000235:genetics; D006801:Humans; D007527:Isoenzymes / Q000737:chemistry* / Q000235:genetics; D008322:Mammals; D016253:Microscopy, Immunoelectron; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D010247:Paramecium / Q000201:enzymology* / Q000235:genetics / Q000648:ultrastructure; D010961:Plasmodium / Q000201:enzymology* / Q000235:genetics; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid; D013768:Tetrahymena / Q000201:enzymology* / Q000235:genetics
chemical_list: D017931:DNA Primers; D007527:Isoenzymes; D006162:Guanylate Cyclase