title: Regulation of competence development and sugar utilization in Haemophilus influenzae Rd by a phosphoenolpyruvate:fructose phosphotransferase system.
abstract: 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.
authors.affiliation: Department of Zoology, University of British Columbia, Vancouver, Canada. lmac@unixg.ubc.ca
authors.forename: L P
authors.initials: LP
authors.lastname: Macfadyen
authors.forename: I R
authors.initials: IR
authors.lastname: Dorocicz
authors.forename: J
authors.initials: J
authors.lastname: Reizer
authors.forename: M H
authors.initials: MH
authors.lastname: Saier
authors.forename: R J
authors.initials: RJ
authors.lastname: Redfield
mesh_terms: D000262:Adenylyl Cyclases / Q000235:genetics; D001692:Biological Transport; D050260:Carbohydrate Metabolism; D003001:Cloning, Molecular; D004789:Enzyme Activation; D005285:Fermentation; D005632:Fructose / Q000378:metabolism; D005690:Galactose / Q000378:metabolism; D005816:Genetic Complementation Test; D005947:Glucose / Q000378:metabolism; D006193:Haemophilus influenzae / Q000235:genetics*; D026901:Membrane Transport Proteins / Q000378:metabolism; D008954:Models, Biological; D016296:Mutagenesis; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000235:genetics* / Q000378:metabolism; D017852:Phosphotransferases (Nitrogenous Group Acceptor) / Q000235:genetics* / Q000378:metabolism; D015183:Restriction Mapping; D017422:Sequence Analysis, DNA; D014170:Transformation, Genetic
chemical_list: D026901:Membrane Transport Proteins; D005632:Fructose; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; D017852:Phosphotransferases (Nitrogenous Group Acceptor); C022360:phosphoenolpyruvate-protein phosphotransferase; D000262:Adenylyl Cyclases; D005947:Glucose; D005690:Galactose