High efficiency temperature-sensitive amber suppressor strains of Escherichia coli K12: construction and characterization of recombinant strains with suppressor-enhancing mutations.

A set of eight strains combining the supD43,74 ts1 suppressor gene with alleles of three suppressor-enhancing (sue) genes have been constructed and characterized. The sue mutations work cooperatively to raise suppressor activity and together raise the activity of the supD43,74-encoded suppressor 40-fold. These strains further expand the utility of the ts suppressor system by providing as much as 100% suppressor activity at temperatures at or below 20 degrees C to as little as 0.015% suppressor activity at 43 degrees C.