Adenylyl cyclase Rv1625c of Mycobacterium tuberculosis: a progenitor of mammalian adenylyl cyclases

• Published in: The EMBO journal Vol. 20; no. 14; pp. 3667 - 3675
• Main Authors: Guo, Ying Lan, Seebacher, Thomas, Kurz, Ursula, Linder, Jürgen U., Schultz, Joachim E.
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 16.07.2001; Blackwell Publishing Ltd; Oxford University Press
• Subjects: adenylyl cyclases; Adenylyl Cyclases - chemistry; Adenylyl Cyclases - genetics; Adenylyl Cyclases - metabolism; Amino Acid Sequence; Amino Acid Substitution; Amino acids; bacterial-eukaryotic expression; Catalysis; Cell Line; Dimerization; E coli; Escherichia coli; Escherichia coli - genetics; evolution; Evolution, Molecular; Humans; Mammals; Membrane Proteins - chemistry; Membrane Proteins - genetics; Membrane Proteins - metabolism; Membranes; Molecular Sequence Data; Mutation; Mycobacterium tuberculosis; Mycobacterium tuberculosis - enzymology; Recombinant Proteins - chemistry; Recombinant Proteins - genetics; Recombinant Proteins - metabolism; Rv1625c gene; Sequence Homology, Amino Acid; Tuberculosis
• ISSN: 0261-4189; 1460-2075; 1460-2075
• DOI: 10.1093/emboj/20.14.3667

The gene Rv1625c from Mycobacterium tuberculosis encodes a membrane‐anchored adenylyl cyclase corresponding to exactly one‐half of a mammalian adenylyl cyclase. An engineered, soluble form of Rv1625c was expressed in Escherichia coli. It formed a homodimeric cyclase with two catalytic centers. Amino acid mutations predicted to affect catalysis resulted in inactive monomers. A single catalytic center with wild‐type activity could be reconstituted from mutated monomers in stringent analogy to the mammalian heterodimeric cyclase structure. The proposed existence of supramolecular adenylyl cyclase complexes was established by reconstitution from peptide‐linked, mutation‐inactivated homodimers resulting in pseudo‐trimeric and ‐tetrameric complexes. The mycobacterial holoenzyme was expressed successfully in E.coli and mammalian HEK293 cells, i.e. its membrane targeting sequence was compatible with the bacterial and eukaryotic machinery for processing and membrane insertion. The membrane‐anchored mycobacterial cyclase expressed in E.coli was purified to homogeneity as a first step toward the complete structural elucidation of this important protein. As the closest progenitor of the mammalian adenylyl cyclase family to date, the mycobacterial cyclase probably was spread by horizontal gene transfer.