Transcription regulators potentially controlled by HPr kinase/phosphorylase in Gram-negative bacteria.
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.
Boël
Grégory
G
Microbiologie et Génétique Moléculaire, CNRS UMR2585, Thiverval-Grignon, France.
Mijakovic
Ivan
I
Mazé
Alain
A
Poncet
Sandrine
S
Taha
Muhamed-Kheir
MK
Larribe
Mireille
M
Darbon
Emmanuelle
E
Khemiri
Arbia
A
Galinier
Anne
A
Deutscher
Josef
J
D000595:Amino Acid Sequence; D001425:Bacterial Outer Membrane Proteins / Q000235:genetics; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D005809:Genes, Regulator; D016680:Genome, Bacterial; D006090:Gram-Negative Bacteria / Q000201:enzymology / Q000235:genetics*; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000235:genetics; D009876:Operon; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000235:genetics / Q000378:metabolism; D010802:Phylogeny; D017346:Protein Serine-Threonine Kinases / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment; D015534:Trans-Activators / Q000235:genetics; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D014158:Transcription, Genetic
D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D009097:Multienzyme Complexes; D015534:Trans-Activators; D014157:Transcription Factors; C112177:osmolarity response regulator proteins; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; C030182:phosphocarrier protein HPr; C110847:HPr kinase; D017346:Protein Serine-Threonine Kinases; C057843:envZ protein, E coli