Roier Sandro, Zingl Franz G, Cakar Fatih, Schild Stefan
Institute of Molecular Biosciences, University of Graz, NAWI Graz, BioTechMed-Graz, Humboldtstraße 50, A-8010 Graz, Austria.
Microb Cell. 2016 May 10;3(6):257-259. doi: 10.15698/mic2016.06.508.
Outer membrane vesicle (OMV) release by Gram-negative bacteria has been observed and studied for decades. First considered as a by-product of cell lysis, it soon became evident that OMVs are actively secreted from the outer membrane (OM) of Gram-negative bacteria. Accordingly, these small particles (~ 10-300 nm in diameter) consist mainly of OM components like phospholipids (PLs), OM proteins, and lipopolysaccharides or lipooligosaccharides. However, OMVs may also comprise periplasmic, inner membrane, or cytoplasmic components. Since the shedding of substantial amounts of OM material represents a significant energy cost to the bacterial cell, OMV production must have some vital biological functions for Gram-negative bacteria. Indeed, intense research on that topic revealed that OMVs play important roles in bacterial physiology and pathogenesis, ranging from secretion and delivery of biomolecules (for example, toxins, DNA, or quorum sensing molecules) over stress response and biofilm formation to immunomodulation and adherence to host cells. Only recently researchers have begun to elucidate the mechanistic aspects of OMV formation, but a general mechanism for the biogenesis of these vesicles is still lacking. Here we review the findings and implications of our recent study published in Nature Communications (Roier S, (2016) Nat. Commun. 7:10515), where we propose a novel and highly conserved bacterial OMV biogenesis mechanism based on PL accumulation in the outer leaflet of the OM. This mechanism might not only have important pathophysiological roles , but also represents the first general mechanism of OMV formation applicable to all Gram-negative bacteria.
革兰氏阴性菌释放外膜囊泡（OMV）的现象已被观察和研究了数十年。OMV最初被认为是细胞裂解的副产物，但很快就发现它是从革兰氏阴性菌的外膜（OM）主动分泌出来的。因此，这些小颗粒（直径约10 - 300纳米）主要由外膜成分组成，如磷脂（PL）、外膜蛋白、脂多糖或脂寡糖。然而，OMV也可能包含周质、内膜或细胞质成分。由于大量外膜物质的脱落对细菌细胞来说是一项巨大的能量消耗，OMV的产生对于革兰氏阴性菌必定具有一些至关重要的生物学功能。事实上，对该主题的深入研究表明，OMV在细菌生理学和发病机制中发挥着重要作用，从生物分子（如毒素、DNA或群体感应分子）的分泌和传递，到应激反应、生物膜形成，再到免疫调节以及与宿主细胞的黏附。直到最近，研究人员才开始阐明OMV形成的机制方面，但这些囊泡生物发生的一般机制仍然缺乏。在此，我们回顾我们发表在《自然通讯》（Roier S，（2016）《自然通讯》7：10515）上的最新研究结果及其意义，我们在该研究中基于磷脂在外膜外小叶中的积累，提出了一种新颖且高度保守的细菌OMV生物发生机制。这种机制不仅可能具有重要的病理生理作用，而且代表了适用于所有革兰氏阴性菌的第一种OMV形成的一般机制。
