Identification of a novel bacteriocin-like protein and structural gene from Rhodococcus erythropolis JCM 2895, using suppression-subtractive hybridization

A novel bacteriocin-like protein and its structural gene (rap) were identified from Rhodococcus erythropolis JCM 2895. The rapA and B genes are located on a 5.4-kb circular plasmid, and were obtained using a modified suppression-subtractive hybridization method. The rapA and B genes were heterologously expressed in Rhodococcus sp. or Escherichia coli, and then characterized. The results indicated that RapA is a small, water-soluble, heat-stable antimicrobial protein, and that RapB is an immunity protein against RapA, estimated to be located on the cell membrane. RapA showed antimicrobial activity particularly against R. erythropolis, and the activity persisted even after SDS-PAGE analysis. For the heterologous expressed RapA protein, N-terminal amino acid sequence was also confirmed. This is the first report of a bacteriocin-like substance obtained from the genus Rhodococcus.