Copyright © 1991, American Society for Microbiology Genetic Analysis of the clII Gene of Bacteriophage HK022

The clII gene product of lambdoid bacteriophages promotes lysogeny by stabilizing the phage-encoded CII protein, a transcriptional activator of the repressor and integrase genes. Previous works showed that the synthesis of the bacteriophage A CIII protein has specific translational requirements imposed by the structure of the mRNA. To gain insight into the mRNA structure and its role in regulating cIII translation, we undertook a mutational analysis of the cIII gene of the related bacteriophage HK022. Our data support the hypothesis that in HK022, as in X, translation initiation requires a specffic mRNA structure. In addition, we found that translation of HK022 cIII, like that of X, is strongly reduced in a host deficient in the endonuclease RNase III. HK022 is a temperate bacteriophage of Escherichia coli (9). Its ability to form viable recombinants with bacterio-phage A shows that it is a member of the lambdoid phage family (10, 25). The lambdoid phages have a similar organi-zation of the genes along the chromosome, which accounts for their ability to form functional hybrids through recombi-nation; their primary sequences, however, are often very divergent (6). The cIII gene of HK022 has been identifie