Studies on Biosynthesis and Morphogenesis of R-type Pyocins of Pseudomonas aeruginosa

Abstract

1. The subunit composition of highly purified pyocin R was reinvestigated by SDS (sodium dodecyl sulfate)-disc electrophoresis by the method of Laemmli (2). At least 22 bands were detected in this way. The molecular weights of these subunits were determined. The localizations of most of these subunits either in the sheath or other portions were determined. The numbers of molecules of each subunit present in one particle of pyocin R were estimated. 2. The precipitability of each subunit by the anti-pyocin R serum was studied by two methods; immunoprecipitation of alkali-dissociated subunits of purified pyocin R and immunoprecipitation of subunit proteins synthesized in vivo. Anti-pyocin R serum precipitated most sheath subunits, but only a few extra-sheath subunits. The probable reason for these results is discussed. 3. No cleavage of structural proteins, including major proteins of the sheath, was observed during pyocin R morphogenesis.