FIGURE 3: Secreted bacteriocins of the Bcn5 family are associated with holin and endolysin genes and can be recognized by the presence of SH3b domains. (A) Environment of genes encoding Bcn5 and six homologs. Note that the homologs of C. perfringens and C. algidicarnis strains are likely to be secreted bacteriocins. (B) Domain analysis of these Bcn5 homologs. SH3b domains as well as a PspA domain and peptidoglycan-binding domains (PG domain) are indicative for a function in the cell wall and hence transport. Note that the Bcn5 homolog of C. manihotivorum, which lacks an association with an holin gene, has none of these domains that would be indicative for a function outside the cytoplasm. See text for further details.