Bifunctional structure of two adenylyl cyclases from the myxobacterium Stigmatella aurantiaca

• Published in: Biochimie Vol. 79; no. 12; pp. 757 - 767
• Main Authors: Coudart-Cavalli, M.P., Sismeiro, O., Danchin, A.
• Format: Journal Article
• Language: English
• Published: France Elsevier Masson SAS 01-12-1997
• Subjects: Adenosine - pharmacology; Adenylate Cyclase Toxin; Adenylyl Cyclases - chemistry; Adenylyl Cyclases - genetics; Adenylyl Cyclases - isolation & purification; Amino Acid Sequence; bacterial differentiation; Bacterial Proteins - chemistry; Bacterial Proteins - genetics; Bacterial Proteins - isolation & purification; Base Sequence; Cyclic AMP - biosynthesis; cyclic nucleotides; Dictyostelium discoideum; DNA Mutational Analysis; Enzyme Activation - drug effects; Escherichia coli; Molecular Sequence Data; multiple adenylyl cyclases; Myxococcales - enzymology; Myxococcales - genetics; Myxococcales - metabolism; Protein Precursors - chemistry; Protein Precursors - genetics; Protein Precursors - isolation & purification; Stigmatella aurantiaca; two component regulatory systems; two component regulatory systems; cyclic nucleotides; bacterial differentiation; multiple adenylyl cyclases
• ISSN: 0300-9084; 1638-6183
• DOI: 10.1016/S0300-9084(97)86934-9

Two adenylyl cyclase genes (
cyaA and
cyaB) from the myxobacterium
Stigmatella aurantiaca were cloned by complementation of
Escherichia coli mutants defective in the
cya gene.
cyaA codes for a protein of 424 amino acid residues (AC1), while
cyaB encodes a protein of 352 residues (AC2). Both cyclases are sensitive to adenosine: cAMP production was strongly inhibited in
E coli cells and cell extracts expressing these genes. AC1 comprises a hydrophobic domain of six transmembrane helices coupled to a cytoplasmic catalytic domain endowed with adenylyl cyclase activity. A 17 amino acid residue sequence, which is a signature of G-protein coupled receptors, as well as of slime mold
Dictyostelium discoideum cyclic AMP receptors, was found in the membrane domain. AC2 displays features also indicating that it is a bifunctional enzyme. The domain located upstream from the catalytic adenylyl cyclase domain shows strong similarity to receiver modules of response regulators of two-component bacterial signaling systems.
In vitro mutagenesis of conserved aspartate residues in this domain was shown to interfere with cAMP synthesis.