Genetic Analysis of Recombination-Deficient Mutants of Escherichia coli K-12 Carrying rec Mutations Cotransducible with thyA

Abstract

The rec mutations carried by 20 strains of Escherichia coli K-12 which are defective in genetic recombination and sensitive to ultraviolet light and X rays, and whose λ lysogens show spontaneous phage production, have been mapped near thyA . In 15 of the strains, the rec mutation fails to complement recB21 but complements rec-22 . The other five strains carry a rec mutation which complements recB21 but not rec-22 . These mutations map closer to thyA than those which fail to complement recB21 . They therefore appear to be defective in a different recombination gene, denoted recC . The order of recB and recC on the linkage map of E. coli K-12 is thyA-recC-recB-argA .