Regulation of the mpt operon in Listeria innocua by the ManR protein

Abstract

The phosphotransferase system regulation domain (PRD)-containing activator, ManR, is required for glucose-controlled transcription of the mannose permease two (mpt) operon in Listeria innocua. His-871 in ManR PRD-II is needed for mpt repression in glucose-free media. His-506 in PRD-I is needed for mpt induction by glucose.

FIG. 1.

Domain organization of the L. innocua Lin11 ManR protein. Protein domains were examined using the InterProScan server (http://www.ebi.ac.uk/InterProScan). Conserved histidines and the boundaries of each domain are numbered. HTH, helix-turn-helix DNA binding domain; EIIA, fructose PTS permease EIIA-like domain. Note that unlike the B. subtilis LevR protein (8), ManR does not appear to contain an EIIB-like domain.

FIG. 2.

Sequence alignment of transcriptional activator (LevR, ManR, LicR, and MtlR) and antiterminator (BglG, LicT, SacT, SacY, and GlcT) PRDs. The BglG sequence is from E. coli (accession no. NP_418179), the ManR sequence is from L. innocua CLIP11262 (http://genolist.pasteur.fr/ListiList), and the other sequences are from B. subtilis (http://genolist.pasteur.fr/SubtiList). Conserved histidines are in bold type and capitalized. The PRD sequences of the Lin11 and CLIP11262 ManR proteins differ only at position 895, where there are glutamate and aspartate residues, respectively.

FIG. 3.

Model for the regulation of ManR activity. In the absence of glucose (Glc), the IIAB^Man subunit of EII_t^Man, which is present in the phosphorylated state, transfers its phosphate to His-871 in PRD-II, inactivating ManR and repressing mpt transcription. His-506 in PRD-I also may be phosphorylated by HPr. In the presence of glucose, the phosphoryl group is transferred from IIAB^Man to the incoming sugar, and ManR is not phosphorylated on His-871. Similarly, fewer ManR molecules are phosphorylated on His-506 in PRD-I by HPr. The monophosphorylated ManR species appears to be active and capable of interacting with RNA polymerase (RNAP), σ⁵⁴, and perhaps Lin0142 to drive transcription of the mpt operon. CM, cytoplasmic membrane; PEP, phosphoenolpyruvate; EI, enzyme I.