Avram and Stella Goldstein-Goren Department of Biotechnology Engineering, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel.
Department of Molecular Biology, Ariel University, Ariel, Israel.
Acta Biomater. 2021 Apr 15;125:231-241. doi: 10.1016/j.actbio.2021.02.015. Epub 2021 Feb 16.
The race drawn against bacteria facing the evolution of antimicrobial resistance fuels research for new drugs and therapeutic strategies. FKF, a tripeptide that is cationic and amphiphilic was examined in light of its potential antimicrobial activity. Acid titration of purified peptide solution, 6% w/v (136 mM), yielded a hydrogel at pH~ 4. Cryo-TEM images of FKF revealed distinct phases formed upon increase in pH, ranging from elongated needles, uniform width fibers, sheets and tubular structures. H NMR attested FKF charged states as function of pH, and CD and FTIR measurements indicated that FKF β-sheet assemblies are held by both π-π stacking and H-bonds. FKF hydrogel displayed bactericidal activity against E. coli and P. aeruginosa with a 3-log reduction in bacterial counts. The hydrogel was also found effective in reducing P. aeruginosa contamination in a skin lesion model in rats. FKF forms a unique antimicrobial peptide-hydrogel, showing neglectable effect in dissolved state, yet only when fibrillary assembled it gains functionality. STATEMENT OF SIGNIFICANCE: Ultra-short peptides are at the frontier of peptide self-assembly research. The tripeptide FKF assumes distinct assembly forms that are a function of pH, for which we have pinpointed the accompanying changes in charge. Made of natural amino acids, FKF forms a pure peptide hydrogel phase, which is intrinsically antimicrobial. We demonstrate that antimicrobial effect is only assumed by the peptide assemblies, posing self-assembly as a pre-requisite for FKF's bactericidal effect. This system provides evidence for the link between specific microscopic peptide assembled structures, macroscopic gel formation and antimicrobial effect, utilized to alleviate bacterial contamination in vivo.
面对抗菌药物耐药性不断进化的细菌，与细菌竞争的研究推动了新药和治疗策略的研发。FKF 是一种带有正电荷和两亲性的三肽，人们研究了其潜在的抗菌活性。对纯化肽溶液（6%w/v，136mM）进行酸滴定，在 pH~4 时得到水凝胶。FKF 的低温透射电镜图像显示，随着 pH 值的增加，会形成明显的不同相，包括长针状、均匀宽度的纤维、片状和管状结构。1H NMR 证明 FKF 的带电状态随 pH 值变化，CD 和 FTIR 测量表明 FKF β-折叠组装由π-π 堆积和氢键共同维持。FKF 水凝胶对大肠杆菌和铜绿假单胞菌具有杀菌活性，可使细菌计数减少 3 个对数。还发现该水凝胶可有效减少大鼠皮肤损伤模型中铜绿假单胞菌的污染。FKF 形成一种独特的抗菌肽水凝胶，在溶解状态下几乎没有作用，但只有在纤维状组装时才具有功能。
超短肽处于肽自组装研究的前沿。三肽 FKF 呈现出依赖于 pH 的独特组装形式，我们已经确定了伴随的电荷变化。由天然氨基酸组成，FKF 形成纯肽水凝胶相，具有内在的抗菌性。我们证明抗菌作用仅由肽组装体承担，这表明自组装是 FKF 杀菌作用的前提。该系统为特定微观肽组装结构、宏观凝胶形成与抗菌作用之间的联系提供了证据，可用于减轻体内细菌污染。
