Gopal Citrupa, Al Tarify Hasan, Pirhadi Emad, O'Brien Eliza G, Dagar Anuradha, Yong Xin, Schertzer Jeffrey W
Department of Biological Sciences, Binghamton University, Binghamton, NY 13902, USA.
Department of Mechanical Engineering, Binghamton University, Binghamton, NY 13902, USA.
Membranes (Basel). 2025 Aug 13;15(8):247. doi: 10.3390/membranes15080247.
Gram-negative bacteria use outer membrane vesicles (OMVs) for toxin trafficking, immune interference, horizontal gene transfer, antibiotic protection, and cell-cell communication. Despite their direct contribution to many pathogenesis-related behaviors, our understanding of how OMVs are produced remains surprisingly incomplete. The Bilayer Couple model describes the induction of OMV formation resulting from the preferential accumulation of small molecules in the outer leaflet of the membrane, resulting in leaflet expansion and membrane bending. Previous work has highlighted the importance of the structure of the Quinolone Signal (PQS) in driving OMV formation, but the nature of interactions with membrane lipids remains unclear. Our recent in silico analysis suggested that a new interaction, between the PQS ring nitrogen and Lipid A, is critical for PQS function. Here, we used chemical analogs to interrogate the importance of specific PQS functional groups in its ability to stimulate OMV biogenesis. We demonstrated that OMV induction requires the presence of all PQS functional groups together. Further modeling uncovered that PQS prefers interaction with the outer leaflet of the membrane, consistent with its unique ability to drive OMV biogenesis. This was explained by much greater hydrogen bond formation between PQS and Lipid A. Interestingly, the preference of PQS for the outer leaflet coincided with that leaflet becoming crowded. Thus, the initial insertion of PQS into the outer leaflet would be expected to encourage local accumulation of more PQS to drive the induction of membrane curvature and subsequent OMV formation.
革兰氏阴性菌利用外膜囊泡（OMV）进行毒素运输、免疫干扰、水平基因转移、抗生素保护和细胞间通讯。尽管它们对许多与发病机制相关的行为有直接贡献，但我们对OMV如何产生的理解仍然惊人地不完整。双层偶联模型描述了由于小分子在外膜小叶中的优先积累导致OMV形成的诱导过程，从而导致小叶扩张和膜弯曲。先前的研究强调了喹诺酮信号（PQS）的结构在驱动OMV形成中的重要性，但与膜脂相互作用的性质仍不清楚。我们最近的计算机模拟分析表明，PQS环氮与脂多糖A之间的一种新相互作用对PQS功能至关重要。在这里，我们使用化学类似物来探究特定PQS官能团在刺激OMV生物合成能力中的重要性。我们证明，OMV诱导需要所有PQS官能团同时存在。进一步的建模发现，PQS更喜欢与膜的外小叶相互作用，这与其驱动OMV生物合成的独特能力一致。这可以通过PQS与脂多糖A之间形成更多的氢键来解释。有趣的是，PQS对外小叶的偏好与该小叶变得拥挤的情况相吻合。因此，预计PQS最初插入外小叶会促进更多PQS的局部积累，从而驱动膜曲率的诱导和随后的OMV形成。
