Transcription initiation sites within an IS2 insertion in a Gal-constitutive mutant of Escherichia coli.

AUTOR(ES)

Hinton, D M

RESUMO

Insertion of the insertion sequence Is2(I) directly before the galE gene of the galactose operon results in a Gal minus phenotype (1, 2). The Gal-constitutive allele galc200 (and its deletion derivative galc200 delta 31) arise from such a Gal minus mutant by the insertion of LS2(II) DNA within the LS2(I) sequence (3). We have transcribed in vitro a DNA template representing the IS2-galE region of galc200 delta 31. Gal-directed transcription initiates at two sites within the IS2(I) sequence, 51 and 52 bp from the IS2-galE junction. The promoter for these transcripts, Pgal200 delta 31, is composed of a novel joint between a -10 region from the IS2(I) DNA and a -35 region contributed by the IS2(II) insertion. No promoters intrinsic to the 121 bp of the IS2(II) sequence also present on the template were detected. The relevance of Pgal200 delta 31 to the Galc phenotype of galc200 and to general mechanisms for the constitutive expression of genes adjacent to IS2 is discussed.

Documentos Relacionados

• IS2 activates the ilvA gene of Pseudomonas cepacia in Escherichia coli.
• Control of transcription of gal repressor and isorepressor genes in Escherichia coli.
• Escherichia coli dicB operon includes a truncated IS2 element.
• IS2 insertion is a major cause of spontaneous mutagenesis of the bacteriophage P1: non-random distribution of target sites.
• gal4 transcription activator protein of yeast can function as a repressor in Escherichia coli.