Structure−Function Relations of Variant and Fragment Nisins Studied with Model Membrane Systems

Abstract

Nisin, a 34 residue lantibiotic produced by strains of Lactococcus lactis subsp. lactis, exerts antimicrobial activity against Gram-positive bacteria at the cytoplasmic membrane. The structural aspects of nisin which facilitate membrane interaction and permeabilization have been investigated in planar lipid bilayers and liposomes with proteolytic fragments and site-directed variants. N-Terminal nisin fragments N1-12 and N1-20 had little effect on phospholipid mobility, on macroscopic electrical conductance, or on calcein release from liposomes. By contrast, the I30W nisin A variant induced a time-dependent reduction in lipid mobility, indicative of nisin-membrane surface interactions, as well as a decline in membrane capacitance, rise in conductance, and calcein release from liposomes. In these respects I30W nisin A is similar to native nisin. Charge substitutions were also engineered to generate K12L and H27K nisin A variants, both of which were similar to I30W nisin A with respect to an overall reduction in phospholipid mobility. While the K12L nisin A variant elicited a higher increase in membrane capacitance and electrical conductance than I30W nisin A, the H27K nisin A variant elicited weaker effects. These results point to a substantial role for intramembrane charged residues in controlling ion flow through nisin-doped membranes. Native nisin and variants elicit an enhanced release of calcein from liposomes composed of the negatively-charged phospholipids cardiolipin and phosphatidylserine, compared with phospholipid bearing no net charge, suggesting that an electrostatic attraction encourages the initial nisin-membrane association. The results are discussed in the context of other recently proposed models for nisin action.

Mode of action of pentocin 31-1: An antilisteria bacteriocin produced by Lactobacillus pentosus from Chinese traditional ham

“…The electrical transmembrane potential (DW), as generated by metabolizing cells, is considered the major driving force for activity. The membrane potential lowers the energy barrier for pore formation (Giffard et al, 1997).…”

Antibacterial Activities of Nisin Z Encapsulated in Liposomes or Produced In Situ by Mixed Culture during Cheddar Cheese Ripening

“…Depolarization of the cell cytoplasmic membrane followed by the efflux of small cytoplasmic components such as amino acids, potassium ions, and ATP led to an instant cessation of all biosynthetic processes (32,39,60). Nisin Z causes an immediate loss of cell K ϩ , phosphate, and ATP in L. monocytogenes, suggesting the unselectivity of these pores (2).…”

Lysine-Oriented Charges Trigger the Membrane Binding and Activity of Nukacin ISK-1

“…Among the structures/functions of lantibiotics, the type A(I) lantibiotic nisin has been explicitly studied to know well the structures responsible for its work as a potential antibiotic. The cationic nature of nisin allows it to bind to the phospholipid membrane by electrostatic interactions (4,12,33), and it exhibits higher affinity to anionic than to zwitterionic model membrane (8). N-terminal backbone amides of nisin interact with the pyrophosphate moiety of lipid II (14), and the transmembrane orientation of the molecule involves the insertion of its C-terminal part for pore formation (30).…”