FIS-induced bending of a region upstream of the promoter activates transcription of the E coli thrU(tufB) operon.
The upstream activator sequence (UAS) of the thrU(tufB) operon, which is the target of the trans-activating protein FIS, has a bent structure. Here we show that the center of bending lies around position -95, between the two FIS-binding regions. Studies with fis+ and fis- cells show that FIS-induced bending of the UAS plays a major role in the trans-activation of the thrU(tufB) operon. This has been concluded from the finding that insertions of small DNA segments, comprising less than one or two complete helix turns, in the junction of the UAS and the RNA polymerase-binding site reduce transcription significantly. Partial restoration of transcriptional activity occurs when one or more full helix turns are inserted. These data are in line with but do not prove that a direct interaction between FIS and RNA polymerase is involved in trans-activation. A role of bending per se resulting from FIS/DNA interaction cannot be excluded.
Verbeek
H
H
Department of Biochemistry, Leiden University, Gorlaeus Laboratories, The Netherlands.
Nilsson
L
L
Bosch
L
L
D001483:Base Sequence; D001665:Binding Sites; D002352:Carrier Proteins / Q000378:metabolism*; D002874:Chromosome Mapping; D004268:DNA-Binding Proteins / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D035021:Factor For Inversion Stimulation Protein; D005686:Galactokinase / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial / Q000235:genetics; D034982:Integration Host Factors; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D009690:Nucleic Acid Conformation; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics*; D014158:Transcription, Genetic / Q000235:genetics*; D015533:Transcriptional Activation
D002352:Carrier Proteins; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D035021:Factor For Inversion Stimulation Protein; D034982:Integration Host Factors; C440502:integration host factor, E coli; D005686:Galactokinase