[Use of uracil-repair selection for extensive DNA sequence deletions]

A procedure for extensive deletion mutagenesis of DNA using the uracil repair system is exemplified by reconstruction of the pBR322 replication regulatory region cloned into M13tg131. By means of an oligonucleotide primer the 116-nucleotide fragment was excised and four nucleotides were introduced to form a BglII restriction site. Use of the uracil repair selection provided a 30-fold increase in the deletion mutagenesis efficiency.