Laboratório de Fisiologia e Bioquímica de Microrganismos, Centro de Biociências e Biotecnologia, Universidade Estadualdo Norte Fluminense Darcy Ribeiro, Campos dos Goytacazes, Rio de Janeiro, Brazil,
Int J Nanomedicine. 2019 Jan 9;14:407-420. doi: 10.2147/IJN.S187957. eCollection 2019.
Plant defensins have a hallmark γ-core motif (GXCXC) that is related to their antimicrobial properties. The aim of this work was to design synthetic peptides based on the region corresponding to the D defensin γ-core that are the smallest amino acid sequences that bear the strongest biological activity.
We made rational substitutions of negatively charged amino acid residues with positively charged ones, and the reduction in length in the selected D γ-core sequence to verify whether the increased net positive charges and shortened length are related to the increase in antifungal activity. Herein, we opted to evaluate the action mechanism of γ D peptide due to its significant inhibitory effect on tested yeasts. In addition, it is the smallest construct comprising only nine amino acid residues, giving it a better possibility to be a prototype for designing a new antifungal drug, with lower costs to the pharmaceutical industry while still maintaining the strongest antimicrobial properties.
The γ D peptide caused the most toxic effects in the yeast , leading to membrane permeabilization, viability loss, endogenous reactive oxygen species increase, the activation of metacaspase, and the loss of mitochondrial functionality, suggesting that this peptide triggers cell death via apoptosis.
We observed that the antifungal activity of D is not strictly localized in the structural domain, which comprises the γ-core region and that the increase in the net positive charge is directly related to the increase in antifungal activity.
植物防御素具有标志性的 γ-核心基序（GXCXC），与它们的抗菌特性有关。这项工作的目的是设计基于与 D 防御素 γ-核心相对应的区域的合成肽，这些肽是具有最强生物学活性的最小氨基酸序列。
我们对带负电荷的氨基酸残基进行了合理的替换，用带正电荷的氨基酸残基进行了替换，并且选择的 D γ-核心序列的长度缩短，以验证净正电荷增加和长度缩短是否与抗真菌活性的增加有关。在这里，我们选择评估 γ D 肽的作用机制，因为它对测试的酵母具有显著的抑制作用。此外，它是由仅九个氨基酸残基组成的最小构建体，使其更有可能成为设计新型抗真菌药物的原型，降低制药行业的成本，同时仍保持最强的抗菌特性。
γ D 肽对酵母产生了最毒的影响，导致膜通透性增加、活力丧失、内源性活性氧增加、介体型半胱天冬酶的激活以及线粒体功能丧失，表明该肽通过细胞凋亡引发细胞死亡。
我们观察到 D 的抗真菌活性并不严格局限于结构域，该结构域包括 γ-核心区域，并且净正电荷的增加与抗真菌活性的增加直接相关。
