Identification of the uvrA6 mutation of Escherichia coli.

The uvrA6 mutation has been cloned on a multicopy plasmid by using a chloramphenicol resistance marker introduced next to the uvrA gene in the Escherichia coli chromosome. The mutation was shown to reside in the N-terminal part of the uvrA gene. Sequencing part of this region of the mutant gene revealed a frameshift mutation at positions 207 to 209, which leads to a stop codon at position 262. A marker rescue experiment showed that this frameshift is the only mutation responsible for the UV-sensitive phenotype of the UvrA6 mutant. The method presented is suitable for the cloning of every chromosomal uvrA mutation and can be useful for the study of the functional domains of the UvrA protein.