A novel heme protein that acts as a carbon monoxide-dependent transcriptional activator in Rhodospirillum rubrum

Abstract

The gene coding for a carbon monoxide-dependent transcriptional activator (cooA) in Rhodospirillum rubrum has been expressed in E. coli, and the recombinant CooA has been purified. CooA contains b-type heme which may act as a CO sensor in vivo. CO-bound CooA was formed when reduced CooA was reacted with CO, but not in the case of oxidized CooA. CooA is the first example of the heme protein acting as a DNA-binding transcriptional activator.