Molecular and Genetic Characterization of a Novel Nisin Variant Produced by Streptococcus uberis

Abstract

Streptococcus uberis is one of the principal causative agents of bovine mastitis. In this study, we report that S. uberis strain 42 produces a lantibiotic, nisin U, which is 78% identical (82% similar) to nisin A from Lactococcus lactis. The 15.6-kb nisin U locus comprises 11 open reading frames, similar in putative functionality but differing in arrangement from that of the nisin A biosynthetic cluster. The nisin U producer strain exhibits specific resistance (immunity) to nisin U and cross-resistance to nisin A, a finding consistent with the 55% sequence similarity of their respective immunity peptides. Homologues of the nisin U structural gene were identified in several additional S. uberis strains, and in each case cross-protective immunity was expressed to nisin A and to the other producers of nisin U and its variants. To our knowledge, this is the first report both of characterization of a bacteriocin by S. uberis, as well as of a member of the nisin family of peptides in a species other than L. lactis.The lactic acid bacterium Streptococcus uberis, in nature primarily found on the lips and skin of cows, in raw milk, and on udder tissue (11), is also a major cause of bovine mastitis (4). Due to the ubiquity of this bacterium in the environment of the dairy cow, teat-end contamination poses a constant threat of infection, and the current level of disease caused by S. uberis remains a persistent problem impacting both on the economic production of milk and on the welfare of the dairy cow (21).Many lactic acid bacteria produce broad-spectrum proteinaceous antimicrobials called bacteriocins, some of which could provide valuable alternatives to traditional therapeutic antibiotics for the treatment of infectious diseases (30). Two such bacteriocins, nisin and lacticin 3147, which are produced by strains of Lactococcus lactis are potential candidates for mastitis control (5, 30). Nisin is the active ingredient in two commercial products: Consept (Applied Microbiology, Inc., New York, NY) and Wipe-Out (ImmuCell, Portland, OR). Lacticin 3147 has also been evaluated as a teat-seal formulation for the prevention of mastitis during the "dry" period in which the cow is not lactating (30).Nisin and lacticin 3147 both belong to the lantibiotic class of bacteriocins (10, 34). The lantibiotics are ribosomally synthesized, low-molecular-weight, heat-stable peptides characterized by their content of posttranslationally modified amino acids, including lanthionine and/or ␤-methyl-lanthionine (22,26,31). Nisin is the most intensively studied lantibiotic (20,35,37). Nisin Z (25) and nisin Q (45) are two natural variants of the original nisin A, differing in their propeptide components from nisin A by one and four amino acids, respectively. Lantibiotic loci typically comprise a structural gene (lanA) and other genes that encode proteins responsible for posttranslational modification of the prepeptide (lanB and lanC, or lanM), proteolytic processing (lanP), transport (lanT), producer selfprotection (lanI and lanEFG), and regulatio...

Isolation and Thermal Stabilization of Bacteriocin Nisin Derived from Whey for Antimicrobial Modifications of Polymers

“…The bacteriocin that belongs to the group of lantibiotics, in several variants differing in amino acid sequence in their structures, is produced by bacterial strains possessing specific genome. The bacteriocins are designated nisin A, nisin Z, nisin Q, F nisin (Lactococcus lactis), and nisin U (Streptococcus uberis) [2][3][4][5][6]. Recently, nisin H variant produced by Streptococcus hyointestinalis was described by O'Connor et al [7].…”

Isolation of a Variant of Subtilosin A with Hemolytic Activity

“…Therefore, the T6I substitution does not affect the interaction with the AlbB immunity peptide, if subtilosin A and AlbB indeed interact. This is not surprising, because a similar cross-immunity is detected between nisin variants and their immunity peptides (33). A producer of nisin U, which is 78% identical (82% similar) to nisin A, shows cross-resistance to nisin A as well as immunity to nisin U.…”

Genetic characterisation and heterologous expression of leucocin C, a class IIa bacteriocin from Leuconostoc carnosum 4010

“…lactis strains (Twomey et al 2002;Zendo et al 2003;de Kwaadsteniet et al 2008). Streptococcus uberis produces an additional variant, nisin U, which is 78% identical to nisin A and shorter in three amino acids than other nisin variants (Wirawan et al 2006).…”