Isolation and characterization of pyocin R1 fibers

By a mild alkaline treatment, pyocin R1 was disassembled into its structural parts, a contracted sheath (and its fragments), a core, and fibers. An alkaline sucrose density gradient centrifugation after this treatment was effective in obtaining fiber-density fractions. The pooled fractions were treated with IgGs against isolated sheaths and isolated cores, simultaneously, and then chromatographed on DEAE-Sepharose CL-6B. The final preparation of fibers purified in this way was confirmed to be homogeneous by electron microscopic observation and an immuno-precipitation reaction. The isolated fiber was found to consist of two major subunit proteins, No. 2 and No. 9, with molecular weights of 71,000 and 31,000, respectively. The fiber exhibited the ability to be adsorbed on sensitive bacterial cells (pseudomonas aeruginosa P14), and to protect against the inactivation of pyocin R1 by a lipopolysaccharide preparation from the bacteria.