A single base-pair change creates a Chi recombinational hotspot in bacteriophage lambda.
X4+ mutations, responsible for the Chi phenotype in phage lambda, locally increase the rate of recombination promoted by the Escherichia coli recombination system (Rec). X+ mutations in the cII gene, one of a few sites in lambda at which such mutations arise, were located genetically and physically with overlapping deletions. DNA sequence analysis of the deletion segment containing the X+ C mutations showed that two independent X+ C mutations arose by the same A-T to T-A transversion. Presumably, this change creates a nucleotide sequence recognized by a protein involved in a rate-limiting step of recombination.
D001483:Base Sequence; D002874:Chromosome Mapping; D003090:Coliphages / Q000235:genetics*; D005814:Genes, Viral; D009154:Mutation; D011995:Recombination, Genetic