Characterization of the major tail protein gpP encoded by Lactobacillus plantarum phage phi gle.

Lactobacillus plantarum temperate phage phi g1e encodes a major virion protein gpP. In the present study, the gpP protein was overproduced in Escherichia coli under plac, and purified. Like the native-gpP protein from phi gle particles (Kakikawa et al., 1996), the purified-gpP protein had an apparent molecular mass of 26.0 kDa on SDS polyacrylamide gel electrophoresis (PAGE), larger than that (18.8 kDa) predicted from the DNA sequence, and was deficient in the first methionine as revealed by the N-terminal protein sequencing. In addition, analysis by immunoelectron microscopy demonstrated that immunogold particles (associated with antigpP-sera) specifically bound to the tails of phi gle particles, indicating that gpP is a main tail component (putatively a tube protein).