Functional consequences of single amino acid substitutions in calmodulin-activated adenylate cyclase of Bordetella pertussis.

Calmodulin-activated adenylate cyclase of Bordetella pertussis and Bacillus anthracis are two cognate bacterial toxins. Three short regions of 13-24 amino acid residues in these proteins exhibit between 66 and 80% identity. Site-directed mutagenesis of four residues in B. pertussis adenylate cyclase situated in the second (Asp188, Asp190) and third (His298, Glu301) segments of identity were accompanied by important decrease, or total loss, of enzyme activity. The calmodulin-binding properties of mutated proteins showed no important differences when compared to the wild-type enzyme. Apart from the loss of enzymatic activity, the most important change accompanying replacement of Asp188 by other amino acids was a dramatic decrease in binding of 3'-anthraniloyl-2'-deoxyadenosine 5'-triphosphate, a fluorescent analogue of ATP. From these results we concluded that the two neighbouring aspartic acid residues in B. pertussis adenylate cyclase, conserved in many other ATP-utilizing enzymes, are essential for binding the Mg(2+)-nucleotide complex, and for subsequent catalysis. Replacement of His298 and Glu301 by other amino acid residues affected the nucleotide-binding properties of adenylate cyclase to a lesser degree suggesting that they might be important in the mechanism of enzyme activation by calmodulin, rather than being involved directly in catalysis

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Aloysia citriodora Palau

Aloysia citriodora Palau, cedron or lemon verbena, is a South American aromatic species widespread in North America, Eurasia, and Africa. It is appreciated because it therapeutic and food (condiment, flavoring) uses. Also is valued as ornamental, insect repellent, and sometimes in perfumery. Its popular culinary and medicinal uses have been expanded from Latin America to the rest of the Western world. Its main active constituents are essential oils, to which owes its aroma and flavor similar to lemon, but also contain flavonoids, verbascosides, iridoids heterosides, and others. It most disseminated uses in folk medicine include those to treat gastrointestinal disorders (digestive, antispasmodic, carminative, antidiarrheal), mild sedative, cardiotonic, febrifuge, analgesic, and antiseptic. Various experimental studies validate different effects, as eupeptic, spasmolytic, antimicrobial, anti-inflammatory, analgesic, hypotensive, among others. Its sedative/anxiolytic activity requires deeper further studies. Of particular interest are its cancer-related effects analyzed to date (antimutagenic, antigenotoxic, and antiangiogenic), and its antioxidant activity linked in various ways to our health.Fil: Hurrell, Julio Alberto. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Laboratorio de Etnobotánica y Botánica Aplicada; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentin