UGA CAN BE DECODED AS TRYPTOPHAN AT LOW EFFICIENCY IN BACILLUS-SUBTILIS

Replacement of cat-86 codon 7 or 144 with the UGA condon permitted the gene to confer chloramphenicol resistance in wild-type Bacillus subtilis. UAA replacement of the same condons resulted in a chloramphenicol-sensitive phenotype in wild-type B. subtilis and a chloramphenicol-resistant phenotype in suppressor-positive strains. N-terminal sequencing showed that UGA at condon 7 was decoded as tryptophan in wild-type cells, at an efficiency of about 6%.