Amino acid and nucleotide sequence, adjacent genes, and heterologous expression of hiracin JM79, a sec-dependent bacteriocin produced by Enterococcus hirae DCH5, isolated from Mallard ducks (Anas platyrhynchos)

The primary structure of a bacteriocin produced by Enterococcus hirae DCH5 was determined by combined amino acid and DNA sequencing. Nucleotide analysis of a 2838-bp DNA fragment of E. hirae DCH5 revealed five putative ORFs. The first orf (hirJM79) encodes a 74-amino-acid peptide containing an N-terminal signal peptide of 30 amino acids, followed by the amino acid sequence of the mature bacteriocin, hiracin JM79 (HirJM79), of 44 amino acids. The second orf (hiriJM79) encodes the putative immunity protein of HirJM79. Contiguous ORFs encode a putative mobilization protein (orfC), a relaxase/mobilization nuclease domain (orfD), and a hypothetical protein (orfE). The production and functional expression of HirJM79 by heterologous hosts suggest that hirJM79 is the minimum requirement for production of biologically active HirJM79, that HirJM79 is most likely externalized by the general secretory pathway or sec-dependent pathway, and that HiriJM79 is the immunity protein for HirJM79.