Transcription of the Escherichia coli recE gene from a promoter in Tn5 and IS50.
Six sbc::Tn5 insertions and one sbc::IS50 insertion, which cause recE expression in Escherichia coli, have been cloned, and their DNA sequences have been determined. The sites of insertion are found at three positions in a 10-bp region: 58, 63, and 68 bp upstream of recE. Primer extension experiments with the cloned Tn5 insertions demonstrate that recE transcripts start adjacent to the insertion elements of five of these mutations and both adjacent and one nucleotide within the insertion element for the sixth mutation. This supports the hypothesis that these mutations have inserted a promoter, and PCR analysis reveals an outward promoter within the distal 69 nucleotides of Tn5. Primer extension analysis of RNA from the uncloned Tn5 and IS50 mutants reveals three additional insertion sites close to the others. Because all the insertions lie in the spacer region between racC and recE, transcribed in sbcA6 and sbc-23 strains, we propose that these insertions be renamed recEs::Tn5 and recEs::IS50.
Department of Molecular and Cell Biology, University of California, Berkeley 94720-3202.
A J
AJ
Clark
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L
Satin
C C
CC
Chu
D001483:Base Sequence; D003001:Cloning, Molecular; D004251:DNA Transposable Elements / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D005090:Exodeoxyribonucleases / Q000235:genetics*; D015870:Gene Expression; D005798:Genes, Bacterial / Q000235:genetics*; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic / Q000235:genetics*; D017422:Sequence Analysis, DNA; D014158:Transcription, Genetic
D004251:DNA Transposable Elements; D029968:Escherichia coli Proteins; D005090:Exodeoxyribonucleases; C038225:recE protein, E coli