1.C.20 The Nisin (Nisin) Family

Many organisms synthesize proteins (or peptides) which are degraded to relatively small hydrophobic or amphipathic, bioactive peptides. These peptides exhibit antibiotic, fungicidal, virucidal, hemolytic and/or tumoricidal activities by interacting with membranes and forming transmembrane channels that allow the free flow of electrolytes, metabolites and water across the phospholipid bilayers. Most of these peptides appear to function in biological warfare. There are many designations given to these bioactive peptides. They include the magainins, cecropins, melittins, defensins, bacteriocidins, etc. The proteins in each family within this functional superfamily are homologous, but they exhibit little or no significant sequence similarity with members of the other families. Thus, each family may have evolved independently. However, certain common structural features observed between members of distinct families suggest that at least some of these families share a common ancestry. The preferential interaction of nisin with cardiolipin-enriched bilayers might explain its antitumor activity by pore-formation in mitochondrial membranes. Small natural molecules, phloretin and capsaicin potentiate the membrane activity of nisin in TOCL-containing membranes (Chernyshova et al. 2022).

The generalized transport reaction catalyzed by channel-forming amphipathic peptides is:

small solutes, electrolytes and water (in) small solutes, electrolytes and water (out).

Bacteriocins are bacterially produced peptide antibiotics with the ability to kill a limited range of bacteria, usually but not always those that are closely related to the producer bacterium. Class II bacteriocins are divided into 5 subclasses:  IIa, linear chain; IIb, two linear chains; IIc, cyclized, IId, linear but different from IIa and IIe, colicin V-like. Many of them exhibit structural features typical of members of the eukaryotic channel-forming amphipathic peptides. That is, they are usually synthesized as small precursor proteins or peptides which are processed with proteolytic elimination of their N-terminal leader sequences, and the resultant mature peptides form one, two or more putative amphipathic transmembrane α-helical spanners (TMSs). For those with two TMSs, a characteristic hinge region that separates the two putative transmembrane segments is usually observed. A similar structural arrangement occurs in the two-TMS Cecropin A proteins (TC #1.C.17).

Many bacteriocins are encoded in operons that also encode an immunity protein and an ABC transport system (TC #3.A.1) with a protease domain at the N-terminus. The ABC systems export the bacteriocins while the protease domains cleave the N-terminal leader sequence. A few bacteriocins are exported by the type II general secretory pathway rather than by ABC-type export systems. In some cases, expression of the bacteriocin-encoding operon is induced by a bacteriocin-like peptide which acts in conjunction with a two component sensor kinase-response regulator to effect induction.

Peptide bacteriocins produced by lactic acid bacteria are categorized into two different classes according to their biochemical and genetic properties (Drider et al., 2006; Nes et al., 2007). Class I peptides are the lantibiotics, which are small, posttranslationally modified peptides that contain unusual amino acids such as lanthionine (1.C.20). Class II includes unmodified bacteriocins which are subdivided into three subclasses, namely, class IIa (pediocin-like bacteriocins), class IIb (two-peptide bacteriocins), and IIc (other [i.e., non-pediocin-like], one-peptide bacteriocins).

Class I lantibiotic bacteriocins are small membrane-active channel-forming peptides of less than 5 kDa. They contain the unusual amino acids lanthionine and β-methyl lanthionine, as well as dehydrated residues. One member of family 1.C.22 (TC #1.C.22.1.2) is the thiol-activated peptide, Lactococcin B, included in Class IIc by Klaenhammer (1993).

Many bacteriocins have been identified in addition to those tabulated in the TC system, but those listed are among the best characterized, with respect to evidence for channel formation in target bacterial membranes. Class III and IV bacteriocins (Klaenhammer, 1993) are large heat-labile proteins that function by mechanisms unrelated to those of the bacteriocins listed here.

Nisin apparently forms channels in bacterial membranes using Lipid II, the prenyl chain-linked donor of the peptidoglycan building block, both as a receptor and as an intrinsic component of the pore (Breukink et al., 2003). The length of the prenyl chain of Lipid II plays an important role in maintaining pore stability. The interaction with Lipid II is required for pore formation, and the pores are stable for seconds. They have a pore diameter of 2-2.5 nm (Wiedemann et al., 2004).

Lantibiotics may kill bacteria by multiple mechanisms. These polycyclic peptides, containing unusual amino acids, have binding specificity for bacterial cells, targeting the bacterial cell wall component lipid II to form pores and thereby lyse the cells. Several members of these lipid II&150;targeted lantibiotics are too short to be able to span the lipid bilayer and cannot form pores, but they maintain their antibacterial efficacy. Hasper et al. (2006) have described an alternative mechanism by which members of the lantibiotic family kill Gram-positive bacteria. This mechanism involves removing lipid II from the cell division site (or septum), thus blocking cell wall synthesis.

 

 


 

References:

Allison, G.E., C. Fremaux, and T.R. Klaenhammer. (1994). Expansion of bacteriocin activity and host range upon complementation of two peptides encoded within the lactacin F operon. J. Bacteriol. 176: 2235-2241.

Breukink, E., H.E. van Heusden, P.J. Vollmerhaus, E. Swiezewska, L. Brunner, S. Walker, A.J.R. Heck, and B. de Kruijff. (2003). Lipid II is an intrinsic component of the pore induced by nisin in bacterial membranes. J. Biol. Chem. 278: 19898-19903.

Brötz, H., M. Josten, I. Wiedemann, U. Schneider, F. Götz, G. Bierbaum, and H.G. Sahl. (1998). Role of lipid-bound peptidoglycan precursors in the formation of pores by nisin, epidermin and other lantibiotics. Mol. Microbiol. 30: 317-327.

Chernyshova, D.N., A.A. Tyulin, O.S. Ostroumova, and S.S. Efimova. (2022). Discovery of the Potentiator of the Pore-Forming Ability of Lantibiotic Nisin: Perspectives for Anticancer Therapy. Membranes (Basel) 12:.

Diep, D.B., L.S. Håvarstein, and I.F. Nes. (1995). A bacteriocin-like peptide induces bacteriocin synthesis in Lactobacillus plantarum C11. Mol. Microbiol. 18: 631-639.

Drider D., G. Fimland, Y. Héchard, L.M. McMullen, H. Prévost. (2006). The continuing story of class IIa bacteriocins. Microbiol Mol Biol Rev. 70: 564-582.

Götz, F., S. Perconti, P. Popella, R. Werner, and M. Schlag. (2014). Epidermin and gallidermin: Staphylococcal lantibiotics. Int. J. Med. Microbiol. 304: 63-71.

Hasper, H.E., N.E. Kramer, J.L. Smith, J.D. Hillman, C. Zachariah, O.P. Kuipers, B. de Kruijff, and E. Breukink. (2006). An alternative bactericidal mechanism of action for lantibiotic peptides that target lipid II. Science 313: 1636-1637.

Klaenhammer, T.R. (1993). Genetics of bacteriocins produced by lactic acid bacteria. FEMS Microbiol. Rev. 12: 39-85.

McAuliffe, O., R.P. Ross, and C. Hill. (2001). Lantibiotics: structure, biosynthesis and mode of action. FEMS Microbiol. Rev. 25: 285-308.

Moll, G.N., W.N. Konings, and A.J.M. Driessen. (1999). Bacteriocins: mechanism of membrane insertion and pore formation. Antonie van Leeuwenhoek 76: 185-198.

Nes I.F., D.B. Diep, H. Holo H. (2007). Bacteriocin diversity in Streptococcus and Enterococcus. J Bacteriol. 189: 1189-1198.

Nes, I.F., D.B. Diep, L.S. Håvarstein, M.B. Brurberg, V. Eijsink, and H. Holo. (1996). Biosynthesis of bacteriocins in lactic acid bacteria. Antonie van Leeuwenhoek 70: 113-128.

Pokhrel, R., N. Bhattarai, P. Baral, B.S. Gerstman, J.H. Park, M. Handfield, and P.P. Chapagain. (2019). Molecular mechanisms of pore formation and membrane disruption by the antimicrobial lantibiotic peptide Mutacin 1140. Phys Chem Chem Phys. [Epub: Ahead of Print]

Pokhrel, R., N. Bhattarai, P. Baral, B.S. Gerstman, J.H. Park, M. Handfield, and P.P. Chapagain. (2021). Lipid II Binding and Transmembrane Properties of Various Antimicrobial Lanthipeptides. J Chem Theory Comput. [Epub: Ahead of Print]

Sahl, H.-G. and G. Bierbaum. (1998). Lantibiotics: biosynthesis and biological activities of uniquely modified peptides from Gram-positive bacteria. Annu. Rev. Microbiol. 52: 41-79.

Smith, L., H. Hasper, E. Breukink, J. Novak, J. Cerkasov, J.D. Hillman, S. Wilson-Stanford, and R.S. Orugunty. (2008). Elucidation of the antimicrobial mechanism of mutacin 1140. Biochem. 47: 3308-3314.

Sun, Z., P. Li, F. Liu, H. Bian, D. Wang, X. Wang, Y. Zou, C. Sun, and W. Xu. (2017). Synergistic antibacterial mechanism of the Lactobacillus crispatus surface layer protein and nisin on Staphylococcus saprophyticus. Sci Rep 7: 265.

Venema, K., G. Venema, and J. Kok. (1995). Lactococcal bacteriocins: mode of action and immunity. Trends Microbiol. 3: 299-304.

Wiedemann, I., R. Benz, and H.-G. Sahl. (2004). Lipid II-mediated pore formation by the peptide antibiotic nisin: a black lipid membrane study. J. Bacteriol. 186: 3259-3261.

Examples:

TC#NameOrganismal TypeExample
1.C.20.1.1

Class I lantibiotic bacteriocin Nisin precursor (has a mersacidin-like Lipid II domain, and forms Lipid II-dependent pores) (Brötz et al., 1998). Its activity is enhanced by the SlpB surface layer protein (Q09FL7) of Lactobacillus crispatus (Sun et al. 2017).

Gram-positive bacteria

Nisin precursor of Lactococcus lactis

 
1.C.20.1.2

Class I lantibiotic bacteriocin Gallidermin precursor (has a mersacidin-like Lipid II domain, and forms Lipid II-dependent pores) (Sahl and Bierbaum, 1998). The genetic organization, biosynthesis, modification, excretion, extracellular activation of the modified pre-peptide by proteolytic processing, self-protection of the producer, gene regulation, structure, and mode of action have been reviewed (Götz et al. 2014). The Gallidermin-lipid II complex probably forms water pores in the membrane (Pokhrel et al. 2019). It complexes Lipid II more tightly than it forms transmembrane channels (Pokhrel et al. 2021).

Firmicutes

Gallidermin precursor of Staphylococcus gallinarum

 
1.C.20.1.3Class I lantibiotic bacteriocin, Pep5 Gram-positive bacteria Pep5 lantibiotic of Staphylococcus epidermidis
 
1.C.20.1.4Class I lantibiotic bacteriocin Mutacin BNY266 Gram-positive bacteria Mutacin of Streptococcus mutans
 
1.C.20.1.5Class I lantibiotic bacteriocin, Subtilin precursor Gram-positive bacteria Subtilin of Bacillus subtilis
 
1.C.20.1.6

Class I lantibiotic bacteriocin, Epidermin precursor (has a mersacidin-like Lipid II domain, and forms Lipid II-dependent pores) (Sahl & Bierbaum, 2008).  The genetic organization, biosynthesis, modification, excretion, extracellular activation of the modified pre-peptide by proteolytic processing, self-protection of the producer, gene regulation, structure, and mode of actionhave been reviewed (Götz et al. 2014).

Firmicutes

Epidermin of Staphylococcus epidermidis

 
1.C.20.1.7Class I lantibiotic bacteriocin, Epilancin K7 precursor Gram-positive bacteria Epilancin K7 of Staphylococcus epidermidis
 
1.C.20.1.8

Mutacin 1140 (MU1140) precursor (homologous to several lantibiotics (Smith et al., 2008)).  MU1140-lipid II complexes form water permeating membrane pores (Pokhrel et al. 2019). A single chain of MU1140 complexed with lipid II allows transport across the membrane via a single-file water transport mechanism. The ordering of the water molecules in the single-file chain region as well as the diffusion behavior is similar to those observed in other biological water channels. Multiple complexes of MU1140-lipid II in the membrane showed enhanced permeability for the water molecules, as well as a noticeable membrane distortion and lipid relocation, suggesting that a higher concentration of MU1140 assembly in the membrane can cause significant disruption of the bacterial membrane (Pokhrel et al. 2019). It complexes Lipid II more tightly than it forms transmembrane channels (Pokhrel et al. 2021).

Bacteria

Mutacin 1140 of Streptococcus mutans (O68586)