Biochem. J. (2006) 396
(215–218) (Printed in Great Britain)
Accelerated Publication
Regulation of prokaryotic adenylyl cyclases by CO2
Arne HAMMER*, David R. W. HODGSON† and Martin J. CANN*1
*School of Biological and Biomedical Sciences, Durham University, South Road, Durham DH1 3LE, U.K., and †Department of Chemistry, Durham University, South Road, Durham DH1 3LE, U.K.
The Slr1991 adenylyl cyclase of the model prokaroyte Synechocystis PCC 6803 was stimulated 2-fold at 20 mM total Ci (inorganic carbon) at pH 7.5 through an increase in kcat. A dose response demonstrated an EC50 of 52.7 mM total Ci at pH 6.5. Slr1991 adenylyl cyclase was activated by CO2, but not by HCO3-. CO2 regulation of adenylyl cyclase was conserved in the CyaB1 adenylyl cyclase of Anabaena PCC 7120. These adenylyl cyclases represent the only identified signalling enzymes directly activated by CO2. The findings prompt an urgent reassessment of the activating carbon species for proposed HCO3--activated adenylyl cyclases.
Key words: adenylyl cyclase (adenyl cyclase, adenylate cyclase), bicarbonate (HCO3-), cAMP, carbon dioxide (CO2), Synechocystis.
Abbreviations used: (s)AC, (soluble) adenylyl cyclase; Ci, inorganic carbon.
1 To whom correspondence should be addressed (email m.j.cann@durham.ac.uk).
Received 8 March 2006/28 March 2006; accepted 30 March 2006
Published as BJ Immediate Publication 30 March 2006, doi:10.1042/BJ20060372
The Biochemical Society, London ©2006
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