Mode of action of lipid II-targeting lantibiotics

High-resolution crystal structure reveals molecular details of target recognition by bacitracin

“…Accordingly, we directly tested bacitracin's membranebinding ability, and found that both zinc and the lipid pyrophosphate target are required for efficient membrane localization. Although consistent with bacitracin acting as an inhibitor of cell-wall biosynthesis, this does not rule out the possibility of membrane perturbation; for example, nisin binds specifically to lipid II and subsequently inserts into the membrane to form pores (31). However, our finding that minimum inhibitory antibiotic concentrations are two orders of magnitude lower than concentrations required to permeabilize bacteria strongly argue that bacitracin's antimicrobial activity stems purely from its ability to sequester undecaprenyl pyrophosphate, and that membrane disruption is an artifact occurring at high concentrations of the drug, and is not required for antibacterial action.…”

“…These structural differences allow us to rationalize the antibiotics' ligand specificity. Nisin recognizes bulky ligands such as lipids II, III, and IV, in which sugars are attached to the pyrophosphate group (31,33); the lantibiotic's open architecture allows it to accommodate these sugar substituents, which are much too large to fit within the compact enclosure formed by bacitracin. Thus, by forming a closed structure that tightly encircles the pyrophosphate group, bacitracin becomes highly specific for undecaprenyl pyrophosphate over lipid II and related molecules.…”

FTIR Spectroscopy for Grape and Wine Analysis

“…Mounting consumer demand for safe alternatives to chemical preservatives such as So 2 has led to a decrease in the quantities added to must and wine, often <0.1 g/L (35)(36)(37)(38). So 2 concentrations in finished wines may therefore be close to the FT-mid-IR detection limit (0.2 g/L).…”

Nisinin Sinerjistik Antimikrobiyel Etkisi

“…Araştırıcılar, lipozom içerisinde bir molekül lipit II'nin bulunması durumunda bile, nisinin bu moleküle yüksek ilgi gösterdiğini ve model membranlarda por oluşturarak sızıntının meydana gelmesine yol açtığını saptamıştır. İleri çalışmalarda, sitoplazmik membranda por oluşumu için öncelikle nisinin N-ucundaki İle-1 aminoasidinin, lipit II'nin fosfat gruplarına bağlandığı, ardından C-ucunun bu molekülle ilişkilendiği ve son aşamada membrana tutunduğu belirlenmiştir [20,23]. (Şekil 1 b ve c).…”