Temperature-sensitive mutation in the initiation codon of the rIIB gene of bacteriophage T4.

We have determined the sequence of a ribosome-protected region of T4 rIIB mRNA labeled in vivo. The rIIB mutant HD263, which is temperature sensitive for translation, has an altered initiation codon (AUA instead of AUG). Because wild-type and HD263 proteins have the same fMet peptide, this AUA is used to initiate translation in the mutant rIIB mRNA. We have also identified a six-base sequence which is complementary to the 3" end of the 16S rRNA.