Transcription antiterminators

Transcription antiterminators controlled by PTS-dependent phosphorylation

These proteins exert positive control of gene expression by transcription antitermination. They regulate the uptake and utilization of specific sugars that are transported by the phosphotransferase system (PTS). Their activity is negatively regulated in the absence of the specific inducer by phosphorylation by the corresponding Enzyme II of the PTS. This results in their inactivity. In the presence of the inducer, the phosphate group is drained to the transported substrate and the active regulators lead to expression of their corresponding catabolic operons. In addition, many PRD-containing regulators are positively controlled by HPr-dependent phosphorylation. This phosphorylation occurs in the absence of glucose and other preferred carbon sources and is part of catabolite repression.

• GlcT: allows expression of the ptsG-ptsH-ptsI operon in the presence of glucose
• LicT: allows expression of the bglS gene and the bglP-bglH operon in the presence of ß-glucosides
• SacT: allows expression of the sacP-sacA operon in the presence of sucrose
• SacY: allows expression of the sacX-sacY operon and the sacB gene in the presence of sucrose

Transcription antiterminators controlled by low molecular weight effectors

• GlpP
• HutP