摘要

抗生素抗性微生物的出现对全球健康构成了令人担忧的威胁。抗菌肽( AMPs )被认为是传统抗生素疗法的可能有效替代物。为了更好地控制和优化它们的杀菌活性，需要了解AMPs的作用机制。植物蛋白EF是一种异二聚体AMP，由植物蛋白E ( PlnE )和植物蛋白F ( PlnF )两种肽组成。我们研究了这些肽在模型脂质双层表面的行为。我们鉴定了促进肽-肽相互作用的残基。我们还鉴定了介导二聚体与膜相互作用的残基。PlnE通过两端的氨基酸与膜相互作用，而只有PlnF的N端接近膜。通过比较两肽细菌素单位点突变体的活性和模拟类脂双层模型表面细菌素的活性，提出了结构活性关系。这些研究使我们能够产生假设，将模拟中观察到的生物物理相互作用与实验测量的活动联系起来。我们发现，当单位点氨基酸取代增强两种肽之间的相互作用时，它们导致明显更强的抗微生物活性，同时它们削弱肽-膜结合。在PlnE突变体( G20A )的情况下，这种作用更明显，它与PlnF相互作用最强，与膜相互作用最弱，同时显示出最高的活性。

The emergence of antibiotic resistant microorganisms poses an alarming threat to global health. Antimicrobial peptides (AMPs) are considered a possible effective alternative to conventional antibiotic therapies. An understanding of the mechanism of action of AMPs is needed in order to better control and optimize their bactericidal activity. Plantaricin EF is a heterodimeric AMP, consisting of two peptides Plantaricin E (PlnE) and Plantaricin F (PlnF). We studied the behavior of these peptides on the surface of a model lipid bilayer. We identified the residues that facilitate peptide–peptide interactions. We also identified residues that mediate interactions of the dimer with the membrane. PlnE interacts with the membrane through amino acids at both its termini, while only the N terminus of PlnF approaches the membrane. By comparing the activity of single-site mutants of the two-peptide bacteriocin and the simulations of the bacteriocin on the surface of a model lipid bilayer, structure activity relationships are proposed. These studies allow us to generate hypotheses that relate biophysical interactions observed in simulations with the experimentally measured activity. We find that single-site amino acid substitutions result in markedly stronger antimicrobial activity when they strengthen the interactions between the two peptides, while, concomitantly, they weaken peptide–membrane association. This effect is more pronounced in the case of the PlnE mutant (G20A), which interacts the strongest with PlnF and the weakest with the membrane while displaying the highest activity.

https://www.sciencedirect.com/science/article/pii/S0005273616000067