Naimi Sabrine, Zirah Séverine, Hammami Riadh, Fernandez Benoît, Rebuffat Sylvie, Fliss Ismail
STELA Dairy Research Center, Institute of Nutrition and Functional Foods, Université Laval, Québec, QC, Canada.
Laboratoire Molécules de Communication et Adaptation des Microorganismes, Muséum National d'Histoire Naturelle, Centre National de la Recherche Scientifique, Sorbonne Universités, Paris, France.
Front Microbiol. 2018 Aug 3;9:1764. doi: 10.3389/fmicb.2018.01764. eCollection 2018.
The bacteriocin microcin J25 (MccJ25) inhibits the growth of Gram-negative pathogens including and species, and . This 21-amino acid peptide has remarkable stability to heat and extreme pH values and resistance to many proteases, thanks to a characteristic lasso structure. In this study, we used the dynamic simulator TIM-1 as gastro-intestinal tract model to evaluate the stability and antibacterial activity of MccJ25 during passage through the proximal portion of the human gastrointestinal tract. MccJ25 concentration was measured in the different simulator sections by HPLC, and inhibition of serotype Enteritidis was evaluated using qualitative and quantitative assays. LC-MS/MS analysis and subsequent molecular networking analysis on the Global Natural Product Social Molecular Networking platform (GNPS) and analysis of the peptide degradation in the presence of proteolytic enzymes mimicking the gastro-intestinal conditions permitted to delineate the fate of MccJ25 through identification of the main degradation products. MccJ25 was relatively stable under gastric conditions, but degraded rapidly in the compartment mimicking the duodenum, notably in the presence of pancreatin. Among pancreatin components, elastase I appeared primarily responsible for MccJ25 breakdown, while α-chymotrypsin was less efficient.
细菌素微菌素J25（MccJ25）可抑制革兰氏阴性病原体的生长，包括大肠杆菌、沙门氏菌和志贺氏菌等。这种由21个氨基酸组成的肽由于其独特的套索结构，对热和极端pH值具有显著的稳定性，并且对多种蛋白酶具有抗性。在本研究中，我们使用动态模拟器TIM-1作为胃肠道模型，以评估MccJ25在通过人类胃肠道近端部分时的稳定性和抗菌活性。通过高效液相色谱法（HPLC）测定不同模拟器部分中的MccJ25浓度，并使用定性和定量分析方法评估肠炎沙门氏菌血清型的抑制情况。在全球天然产物社会分子网络平台（GNPS）上进行液相色谱-串联质谱（LC-MS/MS）分析及后续分子网络分析，并在模拟胃肠道条件的蛋白水解酶存在下分析肽的降解情况，从而通过鉴定主要降解产物来描绘MccJ25的命运。MccJ25在胃部条件下相对稳定，但在模拟十二指肠的隔室中迅速降解，尤其是在存在胰酶的情况下。在胰酶成分中，弹性蛋白酶I似乎是导致MccJ25分解的主要原因，而α-糜蛋白酶的作用较小。
