The PRD domain (for PTS Regulation Domain), is the phosphorylatable regulatory domain found in bacterial transcriptional antiterminator such as BglG, SacY and LicT, as well as in activators such as MtlR and LevR. The PRD is phosphorylated on one or two conserved histidine residues. PRD-containing proteins are involved in the regulation of catabolic operons in Gram+ and Gram- bacteria and are often characterised by a short N-terminal effector domain that binds to either RNA (CAT-RBD for antiterminators Pfam:PF03123) or DNA (for activators), and a duplicated PRD module which is phosphorylated by the sugar phosphotransferase system (PTS) in response to the availability of carbon source. The phosphorylations modify the conformation and stability of the dimeric proteins and thereby the RNA- or DNA-binding activity of the effector domain. The structure of the LicT PRD domains has been solved in both the active (pdb:1h99, [2]) and inactive state (pdb:1tlv [4]), revealing massive structural rearrangements upon activation.

1: Structural insights into the regulation of bacterial signalling proteins containing PRDs. van Tilbeurgh H, Declerck N; Curr Opin Struct Biol 2001;11:685-693. PMID:11751049

2: Crystal structure of an activated form of the PTS regulation domain from the LicT transcriptional antiterminator. van Tilbeurgh H, Le Coq D, Declerck N; EMBO J 2001;20:3789-3799. PMID:11447120

3: Dimer stabilization upon activation of the transcriptional antiterminator LicT. Declerck N, Dutartre H, Receveur V, Dubois V, Royer C, Aymerich S, van Tilbeurgh H; J Mol Biol 2001;314:671-681. PMID:11733988

4: Activation of the LicT transcriptional antiterminator involves a domain swing/lock mechanism provoking massive structural changes. Graille M, Zhou CZ, Receveur-Brechot V, Collinet B, Declerck N, van Tilbeurgh H; J Biol Chem. 2005;280:14780-14789. PMID:15699035