TABLE 1.

The PTS components and their various non-PTS interaction and/or phosphorylation partners

PTS componentNon-PTS phosphorylation/interaction partner(s)Phosphorylation or interactionEffect(s) of phosphorylation or interaction
EI (E. coli)CheA, chemotaxis proteinInteractionStimulates CheA autophosphorylation
P∼EI (B. subtilis)CheA, chemotaxis proteinInteractionInhibits CheA autophosphorylation
HPr (E. coli)Glycogen phosphorylaseInteractionStimulates glycogen phosphorylase activity
P∼His-HPr (E. coli)Glycogen phosphorylaseInteractionPrevents binding of HPr to glycogen phosphorylase
P∼His-HPrAntiterminators, BglG, SacY, LicT, etc.aPhosphorylation in PRD2Stimulates antitermination,b alternate CCR mechanism
Transcription activators, LevR-likePhosphorylation in the EIIAMan domainStimulates transcription, alternate CCR mechanism
Transcription activators, MtlR-likePhosphorylation in PRD2Stimulates transcription, alternate CCR mechanism
Transcription activators, LicR-likePhosphorylation in PRD1 and PRD2Stimulates transcription, alternate CCR mechanism
P∼His-HPr (firmicutes)Glycerol kinase GlpKPhosphorylation, His in the N-terminal halfStimulates GlpK activity, inducer exclusion
LacS, RafP; transporters for lactose, raffinosePhosphorylation in the EIIAGlc domainStimulates substrate/galactose exchange
P-Ser-HPr (firmicutes)CcpAInteractionCCR or CCA, catabolite corepressor
Non-PTS transporters for maltose, ribose, etc.InteractionInducer exclusionc
RbsRInteractionPhysiological role not yet established
P-Ser-Crh (bacilli)CcpAInteractionCCR or CCA, catabolite corepressor
EIIAGlc (enterobacteria)Non-PTS transporters LacY, MalK, MelBInteractionInducer exclusion
Glycerol kinase, GlpKInteraction with the C-terminal domainInducer exclusion
Fermentation respiration switch protein, FrsAInteractionProbably causes increased respiration
P∼EIIAGlc (enterobacteria)Adenylate cyclaseInteractionCCR, activation of adenylate cyclased
P∼EIIADhaDhaL, L subunit of dihydroxyacetone kinasePhosphoryl transferADP bound to DhaL is converted into ATP
EIIBGlc (enterobacteria)MlcInteractionDerepression of genes of the Mlc regulon
P∼EIIBs, Glc/Sac/Lac classAntiterminators, BglG, SacY, LicT, etc.aPhosphorylation in PRD1eInhibits antitermination, induction mechanism
P∼EIIBs, Man/Lac classTranscription activators, LevR-likePhosphorylation in PRD2eInhibits transcription, induction mechanism
P∼EIIBs, Mtl/Gut classTranscription activators, MtlR-likePhosphorylation in the EIIAMtl domaineInhibits transcription, induction mechanism
P∼EIIBs, Lac/Cel classTranscription activators, LicR-likePhosphorylation in the EIIAMtl domaineInhibits transcription, induction mechanism
  • a For a more detailed summary of well-studied antiterminators, see Table 4.

  • b Certain antiterminators (such as SacY and GlcT of B. subtilis) are phosphorylated in vitro by P∼His-HPr in PRD2, but their activity is not stimulated by this modification.

  • c An interaction of P-Ser-HPr with the maltose or ribose transport systems in L. casei and L. lactis has so far not been demonstrated but is suggested from genetic experiments.

  • d An additional cellular factor seems to be necessary for the activation of adenylate cyclase by P∼EIIAGlc (632).

  • e It is not clear whether phosphorylation of the antiterminators/transcription activators occurs via P∼His-HPr and P∼EIIBs stimulate only the phosphoryl transfer or whether the phosphoryl group is transferred from P∼EIIBs to the antiterminators/transcription activators. It is possible that both modes of regulation exist.