Disease relevance of cyaA

• Expression of the cDNA in Escherichia coli resulted in cAMP increase and complemented a catabolic defect in the fermentation of carbohydrates caused by the absence of cAMP in a cyaA mutant [1].
• Adenylate cyclase toxin (ACT), a virulence factor of Bordetella pertussis, acquires hemolytic and toxic activities after post-translational modification of the cyaA gene product, CyaA [2].
• We developed an improved method of linker insertion mutagenesis for introducing 2 or 16 codons into the Bordetella pertussis cyaA gene which encodes a calmodulin-dependent adenylate cyclase [3].
• The predicted gene product of cyaA contains a signal peptide-like domain, a putative sensor domain similar to the gene product of vsrA of Pseudomonas solanacearum, a putative membrane-spanning domain and an adenylate cyclase-like catalytic domain [4].
• Vibrio cholerae and Escherichia coli heat labile toxins (CT and LT) elicit a secretory response from intestinal epithelia by binding apical receptors (ganglioside GM1) and subsequently activating basolateral effectors (adenylate cyclase) [5].

High impact information on cyaA

• Haemolysin is one of a family of membrane-targeted toxins, including the leukotoxins of Pasteurella and Actinobacillus and the bifunctional adenylate cyclase haemolysin of Bordetella pertussis, which require this protoxin activation 1-5 [6].
• Like the guanine nucleotide regulatory proteins, Ns and Ni, which mediate stimulation and inhibition, respectively, of adenylate cyclase, p21 is a membrane-associated GTP binding protein, which exhibits GTPase activity [7].
• The ras oncogene product p21 is not a regulatory component of adenylate cyclase [7].
• These results, combined with the demonstration that lipopolysaccharide inhibits adenylate cyclase activity in P388D1 cells, strongly argues that lipopolysaccharide activation of cells is mediated by a Gi-like receptor-effector coupling protein [8].
• Thus, substitution of an aspartic acid residue for Trp-242 reduced the affinity of adenylate cyclase for CaM greater than 1000-fold [9].

Chemical compound and disease context of cyaA

• Bordetella pertussis adenylate cyclase-hemolysin (AC-Hly), encoded by the cyaA gene, belongs to the RTX family of toxins with extensive glycine-rich repeats in the carboxy-terminal portion [10].
• The inhibition of adenylate cyclase activity of Escherichia coli by methyl alpha-glucoside has been demonstrated in intact or in permeable cells but not in cell-free extracts [11].
• Fructose-specific phosphoenolpyruvate dependent phosphotransferase system of Escherichia coli: its alterations and adenylate cyclase activity [12].
• In Escherichia coli, adenylate cyclase activity in toluene-treated cells can be inhibited by glucose while the activity in a broken cell preparation cannot [13].
• Physiological desensitization of carbohydrate permeases and adenylate cyclase to regulation by the phosphoenolpyruvate:sugar phosphotransferase system in Escherichia coli and Salmonella typhimurium. Involvement of adenosine cyclic 3',5'-phosphate and inducer [14].

Biological context of cyaA

• Deletion analysis shows that a region extending from -569 to -136 bp upstream from the start site of transcription is required for transactivation by bvg, suggesting that multiple binding sites are involved in the activation of the cyaA promoter [15].
• To characterize cis-acting regulatory regions required for the activation of the cyaA gene we constructed cyaA-lacZY fusions containing progressive deletions in the promoter upstream region and isolated promoter mutations by chemical and site-directed mutagenesis [15].
• We placed the cyaA gene and a truncated cyaA gene that lacks the nucleotides that code for a putative C-terminal secretory signal sequence under the control of the lac promoter in the plasmid pUC-19 [16].
• Nucleotide sequence analysis of the region neighboring the cyaA gene revealed that the genes (cyaB, cyaC, and cyaD) encoding the other three subunits (subunits II, III, and IV) were clustered upstream and downstream of the cyaA gene in the order cyaB, cyaA, cyaC, and cyaD and with the same transcription polarity, forming an operon [17].
• Thus, we conclude that the lowered concentration of cAMP in cyaA mutants induces both sigma E and Cpx extracytoplasmic stress regulons and thereby rescues the degP temperature-sensitive phenotype [18].

Anatomical context of cyaA

• B.pertussis AC gene expressed in Escherichia coli produced a calmodulin-dependent enzyme of 200 kd, which lacked lymphocyte penetration capacity [19].
• Adenylate cyclase activity (production of cAMP) depends on the presence of eukaryotic plant calmodulin and is only active after translocation from the prokaryotic cell into the eukaryotic plant cell [20].
• Human erythrocytes bind AC toxin and generate cAMP but are resistant to lysis [21].
• Only one form of AC, of apparent 200 kDa, is a toxin that penetrates eukaryotic cells and generates uncontrolled levels of intracellular cAMP [21].
• Immunoblotting of membranes from sheep erythrocytes throughout the process of cell lysis detects the presence and accumulation of only the 200-kDa form of B. pertussis AC. cAMP generation induced by AC toxin in sheep erythrocytes is immediate whereas appearance of hemolysis is delayed by about 1 h and requires a higher level of AC toxin activity [21].

Associations of cyaA with chemical compounds

• However, introduction of a plasmid harboring the cyaB gene in a cyaA mutant, as well as in a cyaA cyaB mutant, allowed cyclic AMP production [22].
• The cloned P. ruminicola D31d gene was able to complement the cyaA mutation and permitted fermentation of lactose on MacConkey Lactose agar plates [23].
• This glucose effect is partially explained by a glucose inhibition of adenylate cyclase [EC 4.6.1.1; ATP pyrophosphate-lyase(cyclizing)] [24].
• (iii) In permeable cells, potassium phosphate-stimulated adenylate cyclase activity is inhibited by methyl alpha-glucoside or pyruvate; extracts behaved similarly when supplemented with PTS proteins, K2HPO4, and phosphoenolpyruvate [11].
• The protonophore carbonyl cyanide m-chlorophenylhydrazone also inhibits adenylate cyclase activity [25].

Other interactions of cyaA

• Direct interaction between the CTA1 and ARF6 domains in these hybrid proteins reconstituted the adenylate cyclase activity and permitted cAMP-dependent signal transduction in an Escherichia coli reporter system [26].

Analytical, diagnostic and therapeutic context of cyaA

• Western blot analysis of the extract using anti-B.pertussis AC antibodies detected only one protein of 200 kd [19].
• The glucose-specific phosphocarrier protein (IIIGlc) of the bacterial phosphoenolpyruvate:glycose phosphotransferase system (PTS) is a major signal transducer that mediates the intricate interplay among extracellular signals (PTS and non-PTS sugars), cytoplasmic and membrane proteins (PTS and non-PTS transporters), and adenylate cyclase [27].
• Furthermore, the introduced mutation did not reduce the biological activity of the hormone as judged from its action in three biological assay systems: 1) a hormone-sensitive osteoblast adenylate cyclase assay; 2) an in vivo calcium mobilizing assay in rats; and 3) an in vitro bone resorption assay [28].
• This soluble, catalytically active fragment of adenylate cyclase was purified and subjected to amino-terminal sequence analyses; two amino-terminal sequences were identified beginning at residue 82 and at residue 342 of the intact enzyme [29].
• Epitope mapping of 12 monoclonal antibodies (MAbs) directed against AC toxin was conducted to identify regions important for the functional activities of this toxin [30].

References