Replication blockage induces non-homologous deletions in Escherichia coli. The mechanism of the formation of these deletions was investigated. A pBR322-mini-oriC hybrid plasmid carrying two E. coli replication terminators (Ter sites) in opposite orientations was used. Deletions which remove at least the pBR322 blocking site (named Ter1) occurred at a frequency of 2 x 10(-6) per generation. They...

The interaction of the antitumor drug Adriamycin with nucleotides, polynucleotides, RNA, calf thymus nucleosomes, and DNA (including pBR322 supercoiled DNA) has been studied using fluorescent probes. The lanthanide terbium is known to interact with guanine and xanthosine to produce high fluorescence enhancement. The nature of the interaction of the lanthanide with the heterocyclic ring in guani...

The RepA protein of the Rts1 plasmid, consisting of 288 amino acids, is a trans-acting protein essential for replication. A mutant repA gene, repA delta C143, carrying a deletion that removed the 143 C-terminal amino acids of RepA, could transform, but at a low frequency, an Escherichia coli polA strain, JG112, when repA delta C143 was cloned into pBR322 with Rts1 ori in the natural configurati...

The recent electronmicroscopic and biochemical mapping of Z-DNA sites in phi X174, SV40, pBR322 and PM2 DNAs has been used to determine two sets of criteria for identification of potential Z-DNA sequences in natural DNA genomes. The prediction of potential Z-DNA tracts and corresponding statistical analysis of their occurrence have been made on a sample of 14 DNA genomes. Alternating purine and...

The sequences at the splice junctions of many early region 4 (E4) mRNAs from adenovirus 2 (Ad2) were determined by analysis of cDNA clones. The cDNAs were synthesized from poly(A)+ mRNA isolated from HeLa cells early during Ad2 infection. A standard library was constructed, in pBR322, from double stranded cDNAs initiated by oligo-dT priming. Approximately 1% of total recombinants contained E4 s...

The interaction between silver ion and DNA has been followed by submarine gel electrophoresis. When pBR322 plasmid DNA was allowed to interact with silver(I) acetate, it was found to contain Form I and Form II bands whose intensity remained unchanged as the concentration of Ag(+) was increased from 0 to 50 mM. However, the mobility of the bands decreased as the concentration of Ag(+) was increa...