title: Expression of the adenyl cyclase-encoding gene (cya) of Rhizobium meliloti F34: existence of two cya genes?
abstract: To gain insight into the role of cyclic AMP (cAMP) in Gram-negative soil bacteria, we have studied the expression of an adenyl cyclase-encoding gene 'cya' of Rhizobium meliloti F34. In both Escherichia coli and Bradyrhizobium japonicum, the gene is expressed from a promoter(s) contained on a 2.6-kb fragment of the cloned insert, which may indicate the presence of a functional 'cya' promoter or the coincidental presence of sequences which can function as promoters in these two species. The study of 'cya'-lac fusion activity in R. meliloti indicated that the 'cya' gene is not expressed at detectable levels and, thus, may not contribute to the modulation of cAMP levels under the growth conditions employed. R. meliloti strains carrying defined genomic mutations at the 'cya' locus were still capable of the synthesis of near wild-type levels of cAMP. These results suggest that the cloned 'cya' gene is not the key determinant responsible for cAMP synthesis under the culture conditions employed.
authors.affiliation: Microbiology Department, University College, Cork, Ireland.
authors.forename: M
authors.initials: M
authors.lastname: O'Regan
authors.forename: B
authors.initials: B
authors.lastname: Kiely
authors.forename: F
authors.initials: F
authors.lastname: O'Gara
mesh_terms: D000262:Adenylyl Cyclases / Q000235:genetics*; D003001:Cloning, Molecular; D000242:Cyclic AMP / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics; D015870:Gene Expression; D005798:Genes, Bacterial; D005838:Genotype; D005810:Multigene Family; D009154:Mutation; D010957:Plasmids; D015183:Restriction Mapping; D012231:Rhizobium / Q000201:enzymology / Q000235:genetics*
chemical_list: D000242:Cyclic AMP; D000262:Adenylyl Cyclases