Frameshift mutations resulting in the changes of the same amino acid residue (140) in T4 bacteriophage lysozyme and in vivo codons for Trp, Tyr, Met, Val and Ile

The lysozymes of three new strains of double frameshift mutants of T4 bacteriophage, eJ37 eJD3, eJ200 eJD4 and eJ25 eJD1, were isolated from their respective lysates, and their amino acid sequences were compared with that of the wild-type strain. It was found that Trp 138-Tyr-Asn 140 in wild-type lysozyme changes to Met-Val-Tyr in eJ37 eJD3, Tyr 139-Asn 140 to Cys-Ile-Ile in eJ200 eJD4 and Asn 140 to Ile-Ile in eJ25 eJD1. From these results, a new hot spot for frameshift mutations has been found at Asn 140 and in vivo codons for Trp, Tyr, Met, Val and Ile are thought to be UGG, UAU, AUG and AUA, respectively. Nineteen in vivo codons out of 64 codons have been identified by these results together with our previous results.