Institute of Biological, Environmental and Rural Sciences, Aberystwyth University, Aberystwyth, Ceredigion SY23 4DD, UK.
Mol Omics. 2020 Aug 1;16(4):387-397. doi: 10.1039/d0mo00027b. Epub 2020 May 6.
Extracellular membrane vesicles are produced by all domains of life (bacteria, archaea and eukaryotes). Bacterial extracellular vesicles (outer membrane vesicles or OMVs) are produced by outer membrane blebbing, and contain proteins, nucleic acids, virulence factors, lipids and metabolites. OMV functions depend on their internal composition, therefore understanding the proteome of OMVs, and how it varies between organisms, is imperative. Here, we report a comparative proteomic profiling of OMVs from strains of Myxococcus xanthus, a predatory species of Gram-negative myxobacteria whose secretions include secondary metabolites and hydrolytic enzymes, thought to be involved in prey lysis. Ten strains were chosen for study, of which seven had genome sequences available. The remaining three strains were genome sequenced allowing definition of the core and accessory genes and genome-derived proteins found within the pan-genome and pan-proteome respectively. OMVs were isolated from each strain and proteins identified using mass spectrometry. The M. xanthus OMV pan-proteome was found to contain tens of 'core' and hundreds of 'accessory' proteins. Properties of the OMV pan-proteome were compared with those of the pan-proteome deduced from the M. xanthus pan-genome. On average, 80% of 'core' OMV proteins are encoded by genes of the core genome, yet the OMV proteomes of individual strains contain subsets of core genome-derived proteins which only partially overlap. In addition, the distribution of characteristics of vesicle proteins does not correlate with the genome-derived proteome characteristic distribution. We hypothesize that M. xanthus cells package a personalized subset of proteins whose availability is only partially dictated by the presence/absence of encoding genes within the genome.
细胞外膜囊泡由所有生命领域（细菌、古菌和真核生物）产生。细菌细胞外囊泡（外膜囊泡或 OMVs）通过外膜起泡产生，包含蛋白质、核酸、毒力因子、脂质和代谢物。OMV 的功能取决于其内部组成，因此了解 OMV 的蛋白质组及其在不同生物体之间的变化是至关重要的。在这里，我们报告了粘细菌捕食性革兰氏阴性菌 Myxococcus xanthus 菌株的 OMV 比较蛋白质组学分析，其分泌物包括被认为参与猎物裂解的次生代谢物和水解酶。选择了 10 个菌株进行研究，其中 7 个有基因组序列。其余 3 个菌株进行了基因组测序，分别定义了核心和辅助基因以及泛基因组和泛蛋白质组中发现的基因组衍生蛋白。从每个菌株中分离出 OMVs 并使用质谱法鉴定蛋白质。发现 M. xanthus OMV 泛蛋白质组包含数十种“核心”和数百种“辅助”蛋白。将 OMV 泛蛋白质组的特性与从 M. xanthus 泛基因组推断的泛蛋白质组的特性进行了比较。平均而言，80%的“核心”OMV 蛋白由核心基因组基因编码，但个别菌株的 OMV 蛋白质组包含核心基因组衍生蛋白的子集，这些子集仅部分重叠。此外，囊泡蛋白的特征分布与基因组衍生蛋白质组特征分布不相关。我们假设 M. xanthus 细胞包装个性化的蛋白质子集，其可用性仅部分由基因组中编码基因的存在/缺失决定。
