DOUBLE CONDITIONAL LETHALITY - TEMPERATURE-SENSITIVE AND AMBER MUTATIONS IN GLUCOSYL TRANSFERASE GENE OF BACTERIOPHAGE T2

The isolation and characterization of two types of conditional lethal mutations in the α‐glucosyl transferase gene of bacteriophage T2 are described. T2gt7 is temperature‐sensitive for glucosyl transferase by the following criteria: Glucosylation of T2gt7 DNA is temperature‐sensitive in vivo. Compared to T2+ DNA, DNA of the gt7 mutant is two‐thirds glucosylated at 30° and less than 10% glucosylated at 37°. The glucosyl transferase induced by T2gt7 is temperature‐sensitive in vitro. Catalytic activity of the mutant enzyme is rapidly and irreversibly lost at temperature above 37° both in the presence and absence of substrates. The gt7 mutation maps in the T2 gene for glucosyl transferase. T2gt3 is an amber mutation in the T2 gene for glucosyl transferase. DNA of the gt3 mutant is glucosylated in E. coli K704 (supE+) and once glucosylated is not restricted upon growth in E. coli B carrying an amber suppressor. The gt3 mutation also maps in the T2 gene for glucosyl transferase. Copyright © 1969, Wiley Blackwell. All rights reserved