Taxonomic distribution of proteins containing CYCc domains

The CYCc domain within your query sequence starts at position 939 and ends at position 1147, and its E-value is 4.81e-45.

Structure, mechanism, and regulation of mammalian adenylyl cyclase.

Hurley JH
J Biol Chem. 1999; 274: 7599-602

Two amino acid substitutions convert a guanylyl cyclase, RetGC-1, into an adenylyl cyclase.

Tucker CL, Hurley JH, Miller TR, Hurley JB
Proc Natl Acad Sci U S A. 1998; 95: 5993-7

Guanylyl cyclases (GCs) and adenylyl cyclases (ACs) have fundamental roles in a wide range of cellular processes. Whereas GCs use GTP as a substrate to form cGMP, ACs catalyze the analogous conversion of ATP to cAMP. Previously, a model based on the structure of adenylate cyclase was used to predict the structure of the nucleotide-binding pocket of a membrane guanylyl cyclase, RetGC-1. Based on this model, we replaced specific amino acids in the guanine-binding pocket of GC with their counterparts from AC. A change of two amino acids, E925K together with C995D, is sufficient to completely alter the nucleotide specificity from GTP to ATP. These experiments strongly validate the AC-derived RetGC-1 structural model and functionally confirm the role of these residues in nucleotide discrimination.

A polymerase I palm in adenylyl cyclase?

Artymiuk PJ, Poirrette AR, Rice DW, Willett P
Nature. 1997; 388: 33-4

Soluble guanylate cyclase: the forgotten sibling.

Hobbs AJ
Trends Pharmacol Sci. 1997; 18: 484-91

Despite widespread distribution in most mammalian cells, the role of soluble guanylate cyclase has, until recently, been poorly defined, especially when compared with its more illustrious sibling, adenylate cyclase. In this review Adrian Hobbs outlines some of the reasons why the soluble guanylate cyclase-cGMP pathway has remained outside the signalling spotlight for much of the past 30 years. He goes on to describe how new molecular biological and biochemical approaches have facilitated a characterization of soluble guanylate cyclase and how this enzyme has acquired a profound physiological significance, and much research attention, as the intracellular 'receptor' for nitric oxide.

Catalytic mechanism of the adenylyl and guanylyl cyclases: modeling and mutational analysis.

Liu Y, Ruoho AE, Rao VD, Hurley JH
Proc Natl Acad Sci U S A. 1997; 94: 13414-9

The adenylyl and guanylyl cyclases catalyze the formation of 3', 5'-cyclic adenosine or guanosine monophosphate from the corresponding nucleoside 5'-triphosphate. The guanylyl cyclases, the mammalian adenylyl cyclases, and their microbial homologues function as pairs of homologous catalytic domains. The crystal structure of the rat type II adenylyl cyclase C2 catalytic domain was used to model by homology a mammalian adenylyl cyclase C1-C2 domain pair, a homodimeric adenylyl cyclase of Dictyostelium discoideum, a heterodimeric soluble guanylyl cyclase, and a homodimeric membrane guanylyl cyclase. Mg2+ATP or Mg2+GTP were docked into the active sites based on known stereochemical constraints on their conformation. The models are consistent with the activities of seven active-site mutants. Asp-310 and Glu-432 of type I adenylyl cyclase coordinate a Mg2+ ion. The D310S and D310A mutants have 10-fold reduced Vmax and altered [Mg2+] dependence. The NTP purine moieties bind in mostly hydrophobic pockets. Specificity is conferred by a Lys and an Asp in adenylyl cyclase, and a Glu, an Arg, and a Cys in guanylyl cyclase. The models predict that an Asp from one domain is a general base in the reaction, and that the transition state is stabilized by a conserved Asn-Arg pair on the other domain.

New insights on the functions of the guanylyl cyclase receptors.

Wedel BJ, Garbers DL
FEBS Lett. 1997; 410: 29-33

The discovery of at least 29 genes encoding putative guanylyl cyclases in Caenorhabditis elegans has raised the question as to whether there are numerous receptors yet to be discovered in the mammal. The nematode, however, not only seems ideal to study guanylyl cyclase receptor localization and function, given the large variety of isoforms, but also leads to possible identification of ligands for orphan guanylyl cyclases by the use of genetic and behavioral assays. A recent powerful approach to describe the function of different guanylyl cyclase isoforms in mammals has been the disruption of the corresponding genes in the mouse. A salt resistant elevation of blood pressure, which corresponds to the phenotype of 50% of all human patients with essential hypertension, is observed in mice lacking the GC-A-receptor. Mice missing the GC-C receptor have been shown to be resistant to STa, an E. coli heat-stable enterotoxin, which is largely responsible for travellers diarrhea in adults and mortality due to diarrhea in infants.

The conserved asparagine and arginine are essential for catalysis of mammalian adenylyl cyclase.

Yan SZ, Huang ZH, Shaw RS, Tang WJ
J Biol Chem. 1997; 272: 12342-9

Mammalian adenylyl cyclases have two homologous cytoplasmic domains (C1 and C2), and both domains are required for the high enzymatic activity. Mutational and genetic analyses of type I and soluble adenylyl cyclases suggest that the C2 domain is catalytically active and the C1 domain is not; the role of the C1 domain is to promote the catalytic activity of the C2 domain. Two amino acid residues, Asn-1025 and Arg-1029 of type II adenylyl cyclase, are conserved among the C2 domains, but not among the C1 domains, of adenylyl cyclases with 12 putative transmembrane helices. Mutations at each amino acid residue alone result in a 30-100-fold reduction in Kcat of adenylyl cyclase. However, the same mutations do not affect the Km for ATP, the half-maximal concentration (EC50) for the C2 domain of type II adenylyl cyclase to associate with the C1 domain of type I adenylyl cyclase and achieve maximal enzyme activity, or the EC50 for forskolin to maximally activate enzyme activity with or without Gsalpha. This indicates that the mutations at these two residues do not cause gross structural alteration. Thus, these two conserved amino acid residues appear to be crucial for catalysis, and their absence from the C1 domains may account for its lack of catalytic activity. Mutations at both amino acid residues together result in a 3,000-fold reduction in Kcat of adenylyl cyclase, suggesting that these two residues have additive effects in catalysis. A second site suppressor of the Asn-1025 to Ser mutant protein has been isolated. This suppressor has 17-fold higher activity than the mutant and has a Pro-1015 to Ser mutation.

Structure of the adenylyl cyclase catalytic core.

Zhang G, Liu Y, Ruoho AE, Hurley JH
Nature. 1997; 386: 247-53

Mammalian adenylyl cyclases contain two conserved regions, C1 and C2, which are responsible for forskolin- and G-protein-stimulated catalysis. The structure of the C2 catalytic region of type II rat adenylyl cyclase has an alpha/beta class fold in a wreath-like dimer, which has a central cleft. Two forskolin molecules bind in hydrophobic pockets at the ends of cleft. The central part of the cleft is lined by charged residues implicated in ATP binding. Forskolin appears to activate adenylyl cyclase by promoting the assembly of the active dimer and by direct interaction within the catalytic cleft. Other adenylyl cyclase regulators act at the dimer interface or on a flexible C-terminal region.

cGMP as second messenger during Dictyostelium chemotaxis.

vanHaastert PJ, Kuwayama H
FEBS Lett. 1997; 410: 25-8

The chemoattractant cAMP induces directed cell locomotion in Dictyostelium cells. Several second messenger pathways are activated upon binding of cAMP to G-protein-coupled receptors, including adenylyl cyclase, guanylyl cyclase, phospholipase C, and the opening of plasma membrane Ca2+ channels. These second messenger responses are unaltered in many chemotactic mutants, except for the cGMP response. Activation of guanylyl cyclase depends on G-proteins and is regulated by a cGMP-binding protein in a complex manner. This cGMP-binding protein also mediates intracellular functions of cGMP to activate a PKC-related kinase that phosphorylates myosin II heavy chain, thereby allowing myosin filaments to rearrange during cell movement.

Structurally distinct and stage-specific adenylyl cyclase genes play different roles in Dictyostelium development.

Pitt GS, Milona N, Borleis J, Lin KC, Reed RR, Devreotes PN
Cell. 1992; 69: 305-15

We have isolated two adenylyl cyclase genes, designated ACA and ACG, from Dictyostelium. The proposed structure for ACA resembles that proposed for mammalian adenylyl cyclases: two large hydrophilic domains and two sets of six transmembrane spans. ACG has a novel structure, reminiscent of the membrane-bound guanylyl cyclases. An aca- mutant, created by gene disruption, has little detectable adenylyl cyclase activity and fails to aggregate, demonstrating that cAMP is required for cell-cell communication. cAMP is not required for motility, chemotaxis, growth, and cell division, which are unaffected. Constitutive expression in aca- cells of either ACA or ACG, which is normally expressed only during germination, restores aggregation and the ability to complete the developmental program. ACA expression restores receptor and guanine nucleotide-regulated adenylyl cyclase activity, while activity in cells expressing ACG is insensitive to these regulators. Although they lack ACA, which has a transporter-like structure, the cells expressing ACG secrete cAMP constitutively.

Adenylyl cyclases.

Tang WJ, Gilman AG
Cell. 1992; 70: 869-72