Screening recombinant clones containing sequences homologous to Escherichia coli genes using single-stranded...

Detection and isolation of Escherichia coli clones carrying vectors with foreign DNA sequences partially homologous to specific E. coli genes is difficult because denatured DNA in the host genome can hybridize with the probe. In this paper we present a procedure which simplifies this task by using bacteriophage M13 as the cloning vector. The procedure takes advantage of the secretory properties of the phage, as well as the property of nitrocellulose membrane to bind protein and single-stranded DNA but not double-stranded DNA. This procedure is shown to be effective in identifying E. coli clones containing sequences of Chlamydomonas reinhardtii chloroplast DNA that are homologous to the rpoC gene of E. coli. We suggest that this procedure can be used generally for rapid isolation of DNA sequences that are homologous to E. coli genes.