Spx-dependent transcription activation, molecular model. The image shows Spx, the global transcriptional regulator in gram-positive bacteria (red), complexed with DNA-directed RNA polymerase (grey), RNA polymerase sigma factor SigA (blue), the promoter DNA template strand (cyan) and the promoter DNA non-template strand (green). A number of RNA polymerase atoms have been removed in order to show what is going on inside.