Two Groups of Capsule-specific Coliphages Coding for RNA Polymerases with New Promoter Specificities

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Abstract
Four bacteriophages (A16, CK235, .vphi. 1.2 and K31) which specifically attack different encapsulated strains of Escherichia coli have been shown to be related to bacteriophage T7 (which is unable to grow on encapsulated hosts). The conclusion that phages A16 and CK235 are related to T7 is based on (i) similarities in the pattern of expression of intracellular phage proteins, (ii) early appearance, in infected host cells, of a phage DNA-specific RNA polymerase and (iii) hybridization (albeit to a low extent) of A16 DNA and of CK235DNA to T7DNA. The first two criteria also apply to phages .vphi. 1.2 and K31 but hybridization of their DNAs with T7DNA could not detected. The RNA polymerases of CK235 and A16 have similar template specificities and the same applies to the RNA polymerases of .vphi. 1.2 and K31. None of the new RNA polymerases can use T7 DNA as template.