An essential replication gene, repA, of plasmid pSC101 is autoregulated.
Measurements of the rate of replication of a mutant pSC101 plasmid, cloned into a ColE1 vector, showed that insertions of the transposon Tn1000 into the repA gene of pSC101 abolished replication activity, but could be complemented in trans, albeit at a low level. The promoter of the repA gene was mapped by the construction of repA-lacZ gene fusions, and one of the fusions was used to demonstrate that repA protein, provided in trans, could repress expression of beta-galactosidase activity. This repression was primarily due to reduction of transcription of the repA-lacZ fusion. The sequence analysis of mutants of the repA-lacZ fusion gene which were no longer sensitive to the presence of repA protein showed that the site of action of repA was a 22 base-pair sequence, present as an inverted repeat, overlapping the repA promoter. The repA gene is thus autoregulated.
Linder
P
P
Churchward
G
G
Xia
G X
GX
Yu
Y Y
YY
Caro
L
L
D001426:Bacterial Proteins / Q000235:genetics; D002874:Chromosome Mapping; D004261:DNA Replication; D004251:DNA Transposable Elements; D005786:Gene Expression Regulation; D005798:Genes, Bacterial; D009693:Nucleic Acid Hybridization; D009876:Operon; D010957:Plasmids; D014176:Protein Biosynthesis
D001426:Bacterial Proteins; D004251:DNA Transposable Elements