Actinophage R4 as a DNA cloning vector in Streptomyces.

Abstract
Viable deletion mutants of actinophage R4 were isolated using a pyrophosphate treatment. One of the deletion mutants, named R4.DELTA.2, had a deletion of 0.98 megadaltons. A successful cloning of foreign DNA previously cleaved by SmaI endonuclease demonstrated that a unique PvuII site of R4.DELTA.2 DNA was located in a dispensable region. The usefulness of R4 deletion mutants as cloning vectors in Streptomyces is discussed.