in some bacteria, the enzyme is regulated at the transcriptional level. it has been demonstrated that the gene for scs (succd) is transcribed along with the gene for α-ketoglutarate dehydrogenase (sucab) under the control of a promoter called sdhc, which is part of the succinate dehydrogenase operon. this operon is up-regulated by the presence of oxygen and responds to a variety of carbon sources. antibacterial drugs that prevent phosphorylation of histidine, like the molecule ly26650, are potent inhibitors of bacterial scss.