Lactococcal bacteriocins - mode of action and immunity
TL;DR: The lactococcal bacteriocins are hydrophobic cationic peptides, which form pores in the cytoplasmic membrane of sensitive cells.
About: This article is published in Trends in Microbiology.The article was published on 1995-08-01 and is currently open access. It has received 78 citations till now. The article focuses on the topics: Bacteriocin & Antimicrobial peptides.
Summary (2 min read)
Jump to: [Lactococcal bacteriocins: mode of action and immunitv] – [Mode of action of lantlbiotics: nisin] – [REVIEWS] – [Mode of action of non-Iantibiotics Diplococcin] – [Lactostrepcin 5] – [Lactococcins A and B] – [Nisin immunity and resistance] and [Conclusions and perspectives]
Lactococcal bacteriocins: mode of action and immunitv
- It is tempting to assume that different strains of a species produce these substances to enable them to compete for the same ecological niche.
- Class I bacteriocins, or lantibiotics, are small membrane-active peptides that contain the unusual amino acids lanthionine, P-methyllanthionine, dehydroalanine and dehydrobutyrine.
- All the lactococcal bacteriocins that have been thoroughly characterized so far belong to class I or II.
Mode of action of lantlbiotics: nisin
- Nisin is the only lantibiotic produced by L. luctis for which the mode of action has been studied.
- It is active against a broad spectrum of Gram-positive bacteria; Escherichia coli and other Gram-negative bacteria are only affected when their outer membranes are weakened or disrupted by treatment with EDTA or osmotic shock21,22, which makes their inner membrane accessible to the lantibiotic.
REVIEWS
- Nisin has a dual activity against spore-forming bacteria: it inhibits the outgrowth of spores and kills cells in the vegetative state.
- The 2,3_didehydroamino acid residues in nisin are thought to act against spores by interacting with the membrane sulfhydryl groups of germinating spores 23.
- It dissipates the membrane potential of whole cells, cytoplasmic membrane vesicles and artificial membrane vesicles ( liposomes)24125, indicating that the peptide does not require a specific receptor protein for activity or for membrane insertion.
- Membrane disruption is believed to result from the incorporation of nisin into the cytoplasmic membrane to form an ion channel or pore.
- This may account for the differences in sensitivity seen be-tween bacterial species or strains, as permeabilization only occurs in liposomes that contain zwitterionic phospholipids28T2p.
Mode of action of non-Iantibiotics Diplococcin
- The effect of purified diplococcin from L. lactis subsp.
- The addition of 8 arbitrary units of diplococcin to sensitive cells completely abolishes DNA and RNA synthesis within 2 min, which may partially interrupt protein synthesis.
- Small pores allow leakage of protons and other small ions only, whereas amino acids leak through larger pores.
- No receptor is required for nisin activity.
Lactostrepcin 5
- Lactostrepcin 5 (Las.5) and other lactostrepcins have a strong and rapid bactericidal effect on sensitive cells33; only Las5 has been characterized in detail.
- It inhibits uridine uptake and causes leakage of K+ ions and ATP from cells.
- Like diplococcin, Las5 inhibits DNA, RNA and protein synthesis, probably by the inhibition of transport of precursors required for macromolecular synthesis, energy depletion of the cell and/or leakage from the cell of small solutes that are required for various metabolic activities.
- Las5 is equally active against energized and energy-depleted cells33.
Lactococcins A and B
- They belong to a group of small, cationic hydrophobic peptides (including several lantibiotics) that permeabilize membranes28934"6.
- The mode of action of purified lactococcin A has been studied using whole cells of sensitive lactococcal strains and membrane vesicles made from such cells, and also using liposomes obtained from lactococcal phospholipids3'.
- Similar studies on whole cells have also been done using partially purified lactococcin B (Ref. 38) .
- These results indicate that both lactococcins form pores in the cytoplasmic membrane in a voltage-independent manner.
- Low concentrations of lactococcin B allow leakage of protons and ions, whereas ISO-fold more bacteriocin is needed for leakage of glutamate to occur38, which indicates that pores of different sizes can exist.
Nisin immunity and resistance
- There are several mechanisms by which bacteria protect themselves against nisin.
- Nisin resistance (Nis') is not genetically linked to nisin production.
- These results have been united in a model for LciA topology (Fig. 3b ).
- Residues 29-47 are considered to span the cytoplasmic membrane as an amphiphilic a helix by interacting with another transmembrane protein, possibly the lactococcin A receptor.
Conclusions and perspectives
- The past few years have seen significant progress in their understanding of nisin and the lactococcins.
- The structural and immunity genes and the genes encoding the secretion and post-translational modification machinery have been cloned, and the authors are now beginning to understand the modes of action of nisin and the lactococcins A and B, and the way in which the lactococcin A immunity protein LciA works.
- This knowledge, combined with structure-function studies of the bacteriocins, should allow the construction of molecules with enhanced or altered activities and broader specificities for use as, for example, food preservatives.
- A tropism for the mucous membranes of the human respiratory tract; indeed, the upper respiratory tract of humans is virtually the sole reservoir for this organism.
- Infection by H. in/kenzae illustrates the complex interplay that can occur between the host and the pathogen, in a relationship that does not always culminate in disease4.
Did you find this useful? Give us your feedback
Citations
More filters
TL;DR: Aim: Use of a bacteriocin‐producing lactococcal strain to control Listeria monocytogenes in jben.
Abstract: Aim: Use of a bacteriocin-producing lactococcal strain to control Listeria monocytogenes in jben.
Methods and Results: A Lactococcus lactis strain isolated from lben was shown, by the spot technique, to produce a bacteriocin different from nisin. Inhibitory activity of the bacteriocin-producing strain against Listeria monocytogenes was investigated in jben, made from cow's milk fermented with the producer organism and contaminated with 104 or 107 cfu ml−1. Listeria counts were monitored during manufacture, and during conservation at room and at refrigeration temperatures. Results showed that the pathogen was reduced by 2·7 logarithmic units after 30 h of jben processing when the initial inoculum of 107 cfu ml−1 was used. For the initial inoculum of 104 cfu ml−1, the bacterium was completely eliminated at 24 h. Furthermore, the use of the bacteriocin-producing starter culture extended the shelf-life of jben by 5 days.
Conclusions: In situ production of the lactococcal bacteriocin is an efficient biological means of controlling L. monocytogenes in jben and of allowing shelf-life extension.
Significance and Impact of the Study: The proposed technology will essentially benefit minimally processed dairy products and those made with raw milk.
67 citations
Cites background from "Lactococcal bacteriocins - mode of ..."
...The fact that the producer strain is sensitive to nisin provides additional evidence that the bacteriocin produced by the strain isolated in this work is not nisin, as structural (nis A) and immunity (nis I) genes are located on the same operon (Venema et al. 1995)....
[...]
TL;DR: The results provide evidence that the association of bacteriocin-sensitive and -insensitive strains take place in a similar way for cells that have a high or a low natural tolerance towards bacteriOCins, and may preclude the formation of pores with sufficient diameters and lifetimes to ultimately cause cell death.
Abstract: The natural variation in the susceptibilities of gram-positive bacteria towards the bacteriocins nisin and pediocin PA-1 is considerable. This study addresses the factors associated with this variability for closely related lactic acid bacteria. We compared two sets of nonbacteriocinogenic strains for which the MICs of nisin and pediocin PA-1 differed 100- to 1,000-fold: Lactobacillus sake DSM20017 and L. sake DSM20497 and Pediococcus dextrinicus and Pediococcus pentosaccus. Strikingly, the bacteriocin-sensitive and -insensitive strains showed a similar concentration-dependent dissipation of their membrane potential (delta psi) after exposure to these bacteriocins. The bacteriocin-induced dissipation of delta psi below the MICs for the insensitive strains did not coincide with a reduction of intracellular ATP pools and glycolytic rates. This was not observed with the sensitive strains. Analysis of membrane lipid properties revealed minor differences in the phospho- and glycolipid compositions of both sets of strains. The interactions of the bacteriocins with strain-specific lipids were not significantly different in a lipid monolayer assay. Further lipid analysis revealed higher in situ membrane fluidity of the bacteriocin-sensitive Pediococcus strain compared with that for the insensitive strain, but the opposite was found for the L. sake strains. Our results provide evidence that the association of bacteriocins with the cell membrane and their subsequent insertion take place in a similar way for cells that have a high or a low natural tolerance towards bacteriocins. For insensitive strains, overall membrane constitution rather than mere membrane fluidity may preclude the formation of pores with sufficient diameters and lifetimes to ultimately cause cell death.
63 citations
TL;DR: Results indicated that nisin and monolaurin had no action on spores before germination; only pH values had a significant effect (P’≤ 0·001), i.e. spore count decreased as the pH value increased in relation to germination.
Abstract: The effects of nisin and monolaurin, alone and in combination, were investigated on Bacillus licheniformis spores in milk at 37 degrees C. In the absence of inhibitors, germinated spores developed into growing vegetative cells and started sporulation at the end of the exponential phase. In the presence of nisin (25 IU ml-1), spore outgrowth was inhibited (4 log10 reduction at 10 h). Regrowth appeared between 10 and 24 h and reached a high population level (1.25 x 10(8) cfu ml-1) after 7 d. Monolaurin (250 micrograms ml-1) had a bacteriostatic effect during the first 10 h but thereafter, regrowth occurred slowly with a population level after 7 d (4 x 10(5) cfu ml-1) lower than that of nisin. Different combined effects of nisin (between 0 and 42 IU ml-1), monolaurin (ranging from 0 to 300 micrograms ml-1), pH values (between 5.0 and 7.0) and spore loads (10(3), 10(4), 10(5) spores ml-1) were investigated using a Doehlert matrix in order to study the main effects of these factors and the different interactions. Results were analysed using the Response Surface Methodology (RSM) and indicated that nisin and monolaurin had no action on spores before germination; only pH values had a significant effect (P < or = 0.001), i.e. spore count decreased as the pH value increased in relation to germination. Sublethal concentrations of nisin (30 IU ml-1) and monolaurin (100 micrograms ml-1) in combination acted synergistically on outgrown spores and vegetative cells, showing total inhibition at pH 6.0, without regrowth, within 7 d at 37 degrees C.
57 citations
Cites background from "Lactococcal bacteriocins - mode of ..."
...The inhibitory activity of nisin on spores occurred at early germination stage (outgrowth) and could be attributed to the 2,3-didehydroamino acid residues which interact with the membrane sulfhydryl groups of germinating spores (Liu and Hansen 1990; Venema et al. 1995)....
[...]
TL;DR: The gene coding for the immunity protein and the structural gene of microcin E492, a low-molecular-weight channel-forming bacteriocin produced by a strain of Klebsiella pneumoniae, have been characterized and the immunityprotein was found to be associated with the inner membrane.
Abstract: The gene coding for the immunity protein (mceB) and the structural gene of microcin E492 (mceA), a low-molecular-weight channel-forming bacteriocin produced by a strain of Klebsiella pneumoniae, have been characterized. The microcin gene codes for a precursor protein of either 99 or 103 amino acids. Protein sequencing of the N-terminal region of microcin E492 unequivocally identified this gene as the microcin structural gene and indicated that this microcin is synthesized as a precursor protein that is cleaved at either amino acid 15 or 19, at a site resembling the double-glycine motif. The gene encoding the 95-amino-acid immunity protein (mceB) was identified by cloning the DNA segment that encodes only this polypeptide into an expression vector and demonstrating the acquisition of immunity to microcin E492. As expected, the immunity protein was found to be associated with the inner membrane. Analysis of the DNA sequence indicates that these genes belong to the same family as microcin 24, and they do not share structural motifs with any other known channel-forming bacteriocin. The organization of the microcin- and immunity protein-encoding genes suggests that they are coordinately expressed.
52 citations
TL;DR: Recent scientific evidence supports the role of probiotic LAB in mediating many positive health effects and some LAB are currently being assessed for their ability to act as live delivery vectors in the development of new oral vaccines.
Abstract: Fermentation of various foodstuffs by lactic acid bacteria (LAB) is one of the oldest forms of biopreservation practised by mankind. In recent years, significant advances have been made in elucidating the genetic and physiological basis of key LAB traits involved in these industrially significant processes. One important attribute of many LAB is their ability to produce antimicrobial compounds called bacteriocins. Interest in these compounds has grown substantially due to their potential usefulness as natural substitutes for chemical food preservatives in the production of foods with enhanced shelflife and/or safety. There is growing consumer awareness of the link between diet and health. Recent scientific evidence supports the role of probiotic LAB in mediating many positive health effects. In addition, some LAB are currently being assessed for their ability to act as live delivery vectors in the development of new oral vaccines.;
50 citations
References
More filters
TL;DR: The biochemical and genetic characteristics of these antimicrobial proteins are reviewed and common elements are discussed between the different classes of bacteriocins produced by these Gram-positive bacteria.
Abstract: Lactic acid bacteria produce a variety of bacteriocins that have recently come under detailed investigation. The biochemical and genetic characteristics of these antimicrobial proteins are reviewed and common elements are discussed between the different classes of bacteriocins produced by these Gram-positive bacteria.
2,013 citations
TL;DR: The range of inhibitory activity by bacteriocins of lactic acid bacteria can be either narrow, inhibiting only those strains that are closely related to the producer organism, or wide, inhibited a diverse group of Gram-positive microorganisms as mentioned in this paper.
1,754 citations
TL;DR: It is demonstrated that nisin is bactericidal to Salmonella species and that the observed inactivation can be demonstrated in other gram-negative bacteria.
Abstract: Nisin, produced by Lactococcus lactis subsp. lactis, has a broad spectrum of activity against gram-positive bacteria and is generally recognized as safe in the United States for use in selected pasteurized cheese spreads to control the outgrowth and toxin production of Clostridium botulinum. This study evaluated the inhibitory activity of nisin in combination with a chelating agent, disodium EDTA, against several Salmonella species and other selected gram-negative bacteria. After a 1-h exposure to 50 micrograms of nisin per ml and 20 mM disodium EDTA at 37 degrees C, a 3.2- to 6.9-log-cycle reduction in population was observed with the species tested. Treatment with disodium EDTA or nisin alone produced no significant inhibition (less than 1-log-cycle reduction) of the Salmonella and other gram-negative species tested. These results demonstrated that nisin is bactericidal to Salmonella species and that the observed inactivation can be demonstrated in other gram-negative bacteria. Applications involving the simultaneous treatment with nisin and chelating agents that alter the outer membrane may be of value in controlling food-borne salmonellae and other gram-negative bacteria.
586 citations
TL;DR: Transcription analyses of several L. lactis strains indicated that an expression product of the nisA gene, together with NisR, is required for the activation of nisinA transcription, indicating that NisI plays a role in the immunity mechanism.
Abstract: The nisin gene cluster nisABTCIPR of Lactococcus lactis, located on a 10-kbp DNA fragment of the nisin-sucrose transposon Tn5276, was characterized. This fragment was previously shown to direct nisin-A biosynthesis and to contain the nisP and nisR genes, encoding a nisin leader peptidase and a positive regulator, respectively [van der Meer, J. R., Polman, J., Beerthuyzen, M. M., Siezen, R. J., Kuipers, O. P. & de Vos, W. M. (1993) J. Bacteriol. 175, 2578–2588]. Further sequence analysis revealed the presence of four open-reading frames, nisB, nisT, nisC and nisI, downstream of the structural gene nisA. The nisT, nisC and nisI genes were subcloned and expressed individually in Escherichia coli, using the T7-RNA-polymerase system. This resulted in the production of radio-labelled proteins with sizes of 45 kDa (NisC) and 32 kDa (NisI). The nisT gene product was not detected, possibly because of protein instability. The deduced amino acid sequence of NisI contained a consensus Iipoprotein signal sequence, suggesting that this protein is a lipid-modified extracellular membrane-anchored protein. Expression of nisI in L. Iactis provided the cells with a significant level of protection against exogeneously added nisin, indicating that NisI plays a role in the immunity mechanism. In EDTA-treated E. coli cells, expression of nisI conferred up to a 170-fold increase in immunity against nisin A compared to controls. Moreover, a lactococcal strain deficient in nisin-A production, designated NZ9800, was created by gene replacement of nisA by a truncated nisA gene and was 10-fold less resistant to nisin A than the wild-type strain. A wild-type immunity level to nisin and production of nisin was obtained in strain NZ9800 harboring complementing nisA and nisZ plasmids. Transcription analyses of several L. IIactis strains indicated that an expression product of the nisA gene, together with NisR, is required for the activation of nisA transcription.
564 citations
TL;DR: The data suggest that the cytoplasmic membrane is the primary target and that membrane disruption accounts for the bactericidal action of nisin.
Abstract: The peptide antibiotic nisin was shown to cause a rapid efflux of amino acids and Rb+ from the cytoplasm of gram-positive bacteria (Staphylococcus cohnii 22, Bacillus subtilis W 23, Micrococcus luteus ATCC 4698, and Streptococcus zymogenes 24). It strongly decreased the membrane potential of cells as judged by the distribution of the lipophilic tetraphenylphosphonium cation. Ascorbate-phenazine methosulfate-driven transport of L-proline by cytoplasmic membrane vesicles was blocked after addition of nisin, and accumulated amino acids were released from the vesicles. Soybean phospholipid (asolectin) vesicles were not affected by nisin. The data suggest that the cytoplasmic membrane is the primary target and that membrane disruption accounts for the bactericidal action of nisin.
379 citations