Regulation of competence development and sugar utilization in Haemophilus influenzae Rd by a phosphoenolpyruvate:fructose phosphotransferase system

Mol Microbiol. 1996 Sep;21(5):941-52. doi: 10.1046/j.1365-2958.1996.441420.x.


Changes in intracellular cAMP concentration play important roles in Haemophilus influenzae, regulating both sugar utilization and competence for natural transformation. In enteric bacteria, cAMP levels are controlled by the phosphoenolpyruvate:glycose phosphotransferase system (PTS) in response to changes in availability of the preferred sugars it transports. We have demonstrated the existence of a simple PTS in H. influenzae by several methods. We have cloned the H. influenzae ptsI gene, encoding PTS Enzyme I; genome analysis locates it in a pts operon structurally homologous to those of enteric bacteria. In vitro phosphorylation assays confirmed the presence of functional PTS components. A ptsI null mutation reduced fructose uptake to 1% of the wild-type rate, and abolished fructose fermentation even when exogenous cAMP was provided. The ptsI mutation also prevented fermentation of ribose and galactose, but utilization of these cAMP-dependent sugars was restored by addition of cAMP. In wild-type cells the non-metabolizable fructose analogue xylitol prevented fermentation of these sugars, confirming that the fructose PTS regulates cAMP levels. Development of competence under standard inducing conditions was reduced 250-fold by the ptsI mutation, unless cells were provided with exogenous cAMP. Competence is thus shown to be under direct nutritional control by a fructose-specific PTS.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenylyl Cyclases / genetics
  • Biological Transport
  • Carbohydrate Metabolism*
  • Cloning, Molecular
  • Enzyme Activation
  • Fermentation
  • Fructose / metabolism
  • Galactose / metabolism
  • Genetic Complementation Test
  • Glucose / metabolism
  • Haemophilus influenzae / genetics*
  • Membrane Transport Proteins / metabolism
  • Models, Biological
  • Mutagenesis
  • Phosphoenolpyruvate Sugar Phosphotransferase System / genetics*
  • Phosphoenolpyruvate Sugar Phosphotransferase System / metabolism
  • Phosphotransferases (Nitrogenous Group Acceptor) / genetics*
  • Phosphotransferases (Nitrogenous Group Acceptor) / metabolism
  • Restriction Mapping
  • Sequence Analysis, DNA
  • Transformation, Genetic*


  • Membrane Transport Proteins
  • Fructose
  • Phosphoenolpyruvate Sugar Phosphotransferase System
  • Phosphotransferases (Nitrogenous Group Acceptor)
  • phosphoenolpyruvate-protein phosphotransferase
  • Adenylyl Cyclases
  • Glucose
  • Galactose