Nisin biosynthesis

Engelke, G. Gutowski-Eckel, Z. Kiesau, P. Siegers, K. Hammelmann, M. Entian, K.D. Regulation of nisin biosynthesis and immunity in Lactococcus lactis 6F3. Appl. Environ. Microbiol., 60, 814-825 (1994)... 

Several studies (13,14) have indicated that cheese whey could also be used as feedstock for the production of nisin given supplementation of some essential nutrients. However, the systematic investigation of lactic acid formation accompanied by nisin biosynthesis, and the possibility of the simultaneous production of nisin and lactic acid, have not been reported. 

In the present work, the major variables that have significant effects on nisin biosynthesis and lactic acid coproduction from whey were identified, and the optimal conditions for the production of nisin and lactic acid were determined respectively using statistically based experimental designs. In this article, we also discussed the feasibility of simultaneous production of nisin and lactic acid from cheese whey. 

The optimal conditions for nisin biosynthesis and lactic acid formation were obtained by further numerical analysis of the response surface using Design-Expert software and are presented in Table 7. The solution to the maximal nisin biosynthesis was 12.04 g/L for yeast extract, 0.57 g/L for KH2P04, and 0.57 g/L for MgS04. The solution to the maximal lactic acid production was 11.78 g/L for yeast extract, 0.64 g/L for KH2P04, and 0.63... 

Li B, Yu J-PJ, Brunzelle JS, Moll GN, van der Donk WA, Nair SK. Structure and mechanism of the lantibiotic cyclase involved in nisin biosynthesis. Science 2006 311 1464-1467. 

Horn N, Swindell S, Dodd H, Gasson M (1991) Nisin biosynthesis genes are encoded by a novel conjugative transposon. Mol Gen Genet 228 129-135... 

Engelke G, Gutowski-Eckel Z, Kiesau P, Siegers K, Hammelmann M, Entian K-D (1994) Regulation of nisin biosynthesis and immimity in Lactococcus lactis 6F3. Appl Environ Microbiol 60 814-825... 

Cheigh, C.-l., Pyun, Y.-R., 2005. Nisin biosynthesis and its properties. Biotechnology Letters 27, 1641-1648. 

Figure 4 The biosynthesis of nisin A as a representative example of the posttranslational maturation process of lantibiotics. Following ribosomal synthesis, NisB dehydrates serine and threonine residues in the structural region of the prepeptide NisA. NisC subsequently catalyzes intramolecular addition of cysteine residues onto the dehydro amino acids in a stereo- and regioselective manner. Subsequent transport of the final product across the cell membrane by NisT and proteolytic cleavage of the leader sequence by NisP produces the mature lantibiotic. For the sequence of the leader peptide, see Figure 6. Adapted with permission from J. M. Willey W. A. van der Donk, Annu. Rev. Microbiol. 2007, 61, 477-501.

Bo Li was born in China. She received a B.S. in Life Sciences in 2004 from Beijing University. In the fall of 2004, she moved to the University of Illinois at Urbana-Champaign and joined the laboratory of Professor Wilfred A. van der Donk, where she studied the catalytic mechanism of the cyclase involved in the biosynthesis of nisin. Currently, she is focusing on the discovery of novel lantibiotics and the study of unprecedented lantibiotic biosynthetic enzymes. 

A large number of a, 3-didehydro-a-amino acids have been identified as constituents of relatively low molecular weight cyclic compounds from microbial sources. However, the presence of a,p-didehydroalanine in bacterial as well as in mammalian histidine ammonia lyase and in phenylalanine ammonia lyase shows that the occurrence of a,p-didehydro-a-amino acids is not limited to small molecules alone 8 These residues are incorporated in natural sequences by posttranslation modification. a,p-Didehydro-a-amino acids have also been postulated to be precursors in the biosynthesis of several heterocyclic metabolites including penicillin and cephalosporin 9 Other well-known compounds containing ,( -di-dehydro-a-amino acids are nisin 10,11 (a food preservative112 ), subtilin (a broad spectrum antibiotic) 13 and some of the metabolites isolated from Streptomyces strains such as gri-seoviridin 14 ... 

In the current industrial process, nisin is manufactured by fermentation of L. lactis subsp. lactis in a milk-based medium. Biosynthesis of nisin is coupled with the growth of lactic acid bacteria and the production of a significant amount of lactic acid (7). Lactic acid is an important chemical for food processing. It can also be used as a raw material in the production of the biodegradable polymer poly(lactic) acid (12). Unfortunately, lactic acid is not recovered in the current nisin process. 

In 1960, Ramseier [22] discovered that nisin causes leakage of intracellular molecules from cells. Later, it was shown that it disturbs the membrane potential and interferes with energy transdudion [23]. In addition, it causes inhibition of biosynthesis of the cell wall processes by blocking the synthesis of peptidoglycans [24] and by binding to the precursor lipid II [25]. However, micromolar amounts of nisin are needed to permeate artificial membranes [26,27] or to inhibit cell wall synthesis in vitro [28], while the in vivo activity of nisin is in the nanomolar range. As vancomycin, which binds to the peptide motif in lipid II, inhibited the antibacterial activity and... 

The prototypical lantibiotic, nisin, was discovered in 1928 for its antibacterial properties and has been used as a preservative in dairy products since the 1950s (1). Nisin and other lantibiotics exhibit nanomolar efficacy against many Gram-positive strains of bacteria (2), which include methicillin resistant Staphylococcus aureus, vancomycin resistant enterococci, and oxacillin resistant bacteria. On the other hand, some lantibiotics function as morphogenetic peptides rather than antibiotics and are important for spore formation in streptomycetes (3). Since the structural elucidation of nisin in the early 1970s, extensive research efforts have been directed at understanding the biosynthesis and mode of action of various lantibiotics. 

Figure 3 (a) The nisin biosynthetic gene cluster, (b) Posttranslational modifications during the biosynthesis of nisin. Dehydration of serine and threonine residues in the structural region of the precursor peptide NisA is performed by the dehydratase NisB. Then, the (Me)Lan rings are installed by the cyclase NisC. After secretion, the unmodified leader sequence is removed by the serine protease NisP, which generates the biologically active species, (c) The proposed cyclization mechanism for NisC. 

Many questions still remain with respect to both the biosynthesis and the mode of action of lantibiotics. Whereas the targets of the nisin, mersacidin, and cinnamycin groups are now known, the mechanism of action of many other lantibiotics (e.g., lacticin 481, Pep5, and sublancin) is still unclear. Similarly, the biosynthetic pathways still hold many unresolved questions, which include the molecular recognition that allows the synthetases their high level of substrate promiscuity and at the same time provides exquisite control of the regioselectivity of cyclization. 

Wiedemann I, Breukink E, van Kraaij C, Kuipers OP, Bierbaum G, de Kruijff B, Sahl HG. Specific binding of nisin to the peptidoglycan precursor lipid II combines pore formation and inhibition of cell wall biosynthesis for potent antibiotic activity. 

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