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.

中文翻译：

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OMV货物蛋白的种内变异：粘球菌XMV泛蛋白组。

细胞外膜囊泡由生活的所有领域（细菌，古细菌和真核生物）产生。细菌细胞外囊泡（外膜囊泡或OMV）是通过外膜起泡产生的，并含有蛋白质，核酸，致病因子，脂质和代谢产物。OMV的功能取决于其内部组成，因此必须了解OMV的蛋白质组及其在生物之间的变化。在这里，我们报告了比较粘蛋白球菌菌株OMVs的蛋白质组学分析。，是革兰氏阴性黏杆菌的一种掠食性物种，其分泌物包括次生代谢产物和水解酶，被认为与猎物裂解有关。选择了十个菌株进行研究，其中七个具有可用的基因组序列。对其余三个菌株进行基因组测序，以分别定义在泛基因组和泛蛋白质组中发现的核心和辅助基因以及基因组衍生的蛋白质。从每个菌株中分离出OMV，并使用质谱鉴定蛋白质。该黄色粘球菌OMV泛蛋白质被发现含有几十个“核心”和数百个“附件”的蛋白质。将OMV泛蛋白质组的特性与从X.Manthus推断出的泛蛋白质组的特性进行了比较泛基因组。平均而言，“核心” OMV蛋白的80％由核心基因组的基因编码，但单个菌株的OMV蛋白质组包含仅部分重叠的核心基因组衍生蛋白的子集。此外，囊泡蛋白的特征分布与基因组蛋白质组特征分布不相关。我们假设黄单胞菌细胞包装蛋白质的个性化子集，其可用性仅部分取决于基因组内编码基因的存在/不存在。