1. Genetic characterization and heterologous expression of brochocin-C, an antibotulinal, two-peptide bacteriocin produced by Brochothrix campestris ATCC 43754
J K McCormick, A Poon, M Sailer, Y Gao, K L Roy, L M McMullen, J C Vederas, M E Stiles, M J Van Belkum Appl Environ Microbiol. 1998 Dec;64(12):4757-66. doi: 10.1128/AEM.64.12.4757-4766.1998.
Brochocin-C, produced by Brochothrix campestris ATCC 43754, is active against many strains of the closely related meat spoilage organism Brochothrix thermosphacta and a wide range of other gram-positive bacteria, including spores of Clostridium botulinum. Purification of the active compound and genetic characterization of brochocin-C revealed that it is a chromosomally encoded, two-peptide nonlantibiotic bacteriocin. Both peptides of brochocin-C are ribosomally synthesized as prepeptides that are typical of class II bacteriocins. They are cleaved following Gly-Gly cleavage sites to yield the mature peptides, BrcA and BrcB, containing 59 and 43 amino acids, respectively. Fusion of the nucleotides encoding the signal peptide of the bacteriocin divergicin A in front of the structural genes for either BrcA or BrcB allowed independent expression of each component by the general protein secretion pathway. This revealed the two-component nature of brochocin-C and the necessity for both peptides for activity. A 53-amino-acid peptide encoded downstream of brcB functions as the immunity protein (BrcI) for brochocin-C. In addition, the cloned chromosomal fragment revealed open reading frames downstream of brcI, designated brcT and brcD, that encode proteins with homology to ATP-binding cassette translocator and accessory proteins, respectively, involved in the secretion of Gly-Gly-type bacteriocins.
2. Brochocin-C, a new bacteriocin produced by Brochothrix campestris
G R Siragusa, C N Cutter Appl Environ Microbiol. 1993 Jul;59(7):2326-8. doi: 10.1128/aem.59.7.2326-2328.1993.
Brochotrix campestris ATCC 43754 produces a bacteriocin inhibitory towards Brochothrix thermosphacta, lactobacilli, Listeria spp., and other gram-positive bacteria. This antimicrobial agent is heat stable, sensitive to proteases, catalase insensitive, and free of organic acids. No phage particles were detected by transmission electron microscopy. Muramidase activity was not detected in the preparations. On the basis of established criteria, the antimicrobial agent was classified as a bacteriocin and named brochocin-C.
3. The outer membrane of gram-negative bacteria inhibits antibacterial activity of brochocin-C
Y Gao, M J van Belkum, M E Stiles Appl Environ Microbiol. 1999 Oct;65(10):4329-33. doi: 10.1128/AEM.65.10.4329-4333.1999.
Brochocin-C is a two-peptide bacteriocin produced by Brochothrix campestris ATCC 43754 that has a broad activity spectrum comparable to that of nisin. Brochocin-C has an inhibitory effect on EDTA-treated gram-negative bacteria, Salmonella enterica serovar Typhimurium lipopolysaccharide mutants, and spheroplasts of Typhimurium strains LT2 and SL3600. Brochocin-C treatment of cells and spheroplasts of strains of LT2 and SL3600 resulted in hydrolysis of ATP. The outer membrane of gram-negative bacteria protects the cytoplasmic membrane from the action of brochocin-C. It appears that brochocin-C is similar to nisin and possibly does not require a membrane receptor for its function; however, the difference in effect of the two bacteriocins on intracellular ATP indicates that they cause different pore sizes in the cytoplasmic membrane.
