Regulation of prokaryotic adenylyl cyclases by CO2.
The Slr1991 adenylyl cyclase of the model prokaroyte Synechocystis PCC 6803 was stimulated 2-fold at 20 mM total C(i) (inorganic carbon) at pH 7.5 through an increase in k(cat). A dose response demonstrated an EC50 of 52.7 mM total C(i) 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.
School of Biological and Biomedical Sciences, Durham University, South Road, Durham DH1 3LE, UK.
Arne
A
Hammer
David R W
DR
Hodgson
Martin J
MJ
Cann
D000262:Adenylyl Cyclases / Q000378:metabolism*; D001639:Bicarbonates / Q000378:metabolism / Q000494:pharmacology; D002245:Carbon Dioxide / Q000378:metabolism / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D011387:Prokaryotic Cells / Q000201:enzymology* / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D046939:Synechocystis / Q000201:enzymology / Q000378:metabolism
D001639:Bicarbonates; D011994:Recombinant Proteins; D002245:Carbon Dioxide; D000262:Adenylyl Cyclases