title: Control of Transposon-Mediated Directed Mutation by the Escherichia coli Phosphoenolpyruvate:Sugar Phosphotransferase System.
abstract: The phosphoenolpyruvate:sugar phosphotransferase system (PTS) has been shown to control transport, cell metabolism and gene expression. We here present results supporting the novel suggestion that in certain instances it also regulates the mutation rate. Directed mutations are defined as mutations that occur at higher frequencies when beneficial than when neutral or detrimental. To date, the occurrence of directed point mutations has not been documented and confirmed, but a few examples of transposon-mediated directed mutations have been reported. Here we focus on the first and best-studied example of directed mutation, which involves the regulation of insertion sequence-5 hopping into a specific site upstream of the glpFK glycerol utilization operon in Escherichia coli. This insertional event specifically activates expression of the glpFK operon, allowing the growth of wild-type cells with glycerol as a carbon source in the presence of nonmetabolizable glucose analogues which normally block glycerol utilization. The sugar-transporting PTS controls this process by regulating levels of cytoplasmic glycerol-3-phosphate and cyclic (c)AMP as established in previous publications. Direct involvement of the glycerol repressor, GlpR, and the cAMP receptor protein, Crp, in the regulation of transposon-mediated directed mutation has been demonstrated.
authors.affiliation: Department of Molecular Biology, Division of Biological Sciences, University of California at San Diego, La Jolla, Calif., USA.
authors.forename: Milton H
authors.initials: MH
authors.lastname: Saier
authors.forename: Zhongge
authors.initials: Z
authors.lastname: Zhang
mesh_terms: D002373:Cyclic AMP Receptor Protein / Q000235:genetics / Q000378:metabolism; D004251:DNA Transposable Elements; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000235:genetics* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D005947:Glucose / Q000378:metabolism; D005990:Glycerol / Q000378:metabolism; D016254:Mutagenesis, Insertional; D009154:Mutation; D009876:Operon; D010728:Phosphoenolpyruvate / Q000378:metabolism; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000235:genetics* / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D002373:Cyclic AMP Receptor Protein; D004251:DNA Transposable Elements; D029968:Escherichia coli Proteins; C101651:GlpR protein, E coli; D012097:Repressor Proteins; D010728:Phosphoenolpyruvate; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; D005947:Glucose; D005990:Glycerol