2-oxoglutarate enhances NtcA binding activity to promoter regions of the microcystin synthesis gene cluster

► New putative NtcA boxes identified in mcy promoters (Microcystis aeruginosa PCC7806). ► 2-oxoglutartate increased the affinity of NtcA for the mcyA promoter region. ► Data suggest that NtcA acts in this case as a repressor of microcystin synthesis. ► Data suggest that microcystin synthesis is regulated responding to the C/N balance.