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The origin of replication of plasmid pSC101 contains three directly repeated sequences RS1, RS2, and RS3 separated by 22 bp from two palindromic sequences, IR1 and IR2, which are partially homologous to the direct repeats. These inverted repeat (IR) sequences overlap the promoter of the repA gene which encodes a protein essential for plasmid replication. We(More)
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(More)
We have isolated a high copy number mutant of plasmid pSC101 which is maintained at a level 4 times higher than that of the wild type. The mutation is a single base change that maps in codon 93 of the initiation protein RepA. We find that the mutation relaxes the autoregulation of the protein but increases its affinity for the repeated sequences in the(More)
OBJECTIVE To clone the gene encoding methyl-accepting chemotaxis signal transduction protein (MCSTP) of Helicobacter hepaticus and analyze the gene structures using bioinformatics methods. METHODS With the specific primer of Helicobacter hepaticus MCSTP c1977, MCSTP gene was amplified by PCR from the genomic DNA of Helicobacter hepaticus and ligated to(More)
Copy-number mutants of plasmid pSC101 were isolated by u.v. mutagenesis and selection for elevated expression of ampicillin resistance. Three independent mutations were identical and mapped in codon 93 of the initiation protein RepA. The mutated plasmids were maintained at a level four to five times higher than that of the wild type. For one of them, it was(More)
The RepA replication protein of plasmid pSC101 binds as a monomer to three repeated sequences (RS1, RS2, and RS3) in the replication origin of the plasmid to initiate duplication and binds as a dimer to two inversely repeated sequences (IR1 and IR2) in its promoter region (D. Manen, L. C. Upegui-Gonzalez, and L. Caro, Proc. Natl. Acad. Sci. USA(More)
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