Transcription regulators potentially controlled by HPr kinase/phosphorylase in Gram-negative bacteria

J Mol Microbiol Biotechnol. 2003;5(4):206-15. doi: 10.1159/000071072.


Phosphorylation and dephosphorylation at Ser-46 in HPr, a phosphocarrier protein of the phosphoenolpyruvate:carbohydrate phosphotransferase system (PTS) is controlled by the bifunctional HPr kinase/phosphorylase (HprK/P). In Gram-positive bacteria, P-Ser-HPr controls (1) sugar uptake via the PTS; (2) catabolite control protein A (CcpA)-mediated carbon catabolite repression, and (3) inducer exclusion. Genome sequencing revealed that HprK/P is absent from Gram-negative enteric bacteria, but present in many other proteobacteria. These organisms also possess (1) HPr, the substrate for HprK/P; (2) enzyme I, which phosphorylates HPr at His-15, and (3) one or several enzymes IIA, which receive the phosphoryl group from P approximately His-HPr. The genes encoding the PTS proteins are often organized in an operon with HPRK. However, most of these organisms miss CcpA and a functional PTS, as enzymes IIB and membrane-integrated enzymes IIC seem to be absent. HprK/P and the rudimentary PTS phosphorylation cascade in Gram-negative bacteria must therefore carry out functions different from those in Gram-positive organisms. The gene organization in many HprK/P-containing Gram-negative bacteria as well as some preliminary experiments suggest that HprK/P might control transcription regulators implicated in cell adhesion and virulence. In alpha-proteobacteria, HPRK is located downstream of genes encoding a two-component system of the EnvZ/OmpR family. In several other proteobacteria, HPRK is organized in an operon together with genes from the RPON region of ESCHERICHIA COLI (RPON encodes a sigma54). We propose that HprK/P might control the phosphorylation state of HPr and EIIAs, which in turn could control the transcription regulators.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Amino Acid Sequence
  • Bacterial Outer Membrane Proteins / genetics
  • Bacterial Proteins*
  • Escherichia coli Proteins*
  • Genes, Regulator
  • Genome, Bacterial
  • Gram-Negative Bacteria / enzymology
  • Gram-Negative Bacteria / genetics*
  • Molecular Sequence Data
  • Multienzyme Complexes / genetics
  • Operon
  • Phosphoenolpyruvate Sugar Phosphotransferase System / genetics
  • Phosphoenolpyruvate Sugar Phosphotransferase System / metabolism
  • Phylogeny
  • Protein-Serine-Threonine Kinases / genetics*
  • Protein-Serine-Threonine Kinases / metabolism
  • Sequence Alignment
  • Trans-Activators / genetics
  • Transcription Factors / genetics*
  • Transcription Factors / metabolism
  • Transcription, Genetic


  • Bacterial Outer Membrane Proteins
  • Bacterial Proteins
  • Escherichia coli Proteins
  • Multienzyme Complexes
  • Trans-Activators
  • Transcription Factors
  • osmolarity response regulator proteins
  • Phosphoenolpyruvate Sugar Phosphotransferase System
  • phosphocarrier protein HPr
  • HPr kinase
  • Protein-Serine-Threonine Kinases
  • envZ protein, E coli