Life Sciences Division, Lawrence Berkeley National Laboratory Berkeley, CA, USA ; Department of Molecular and Cell Biology, University of California, Berkeley Berkeley, CA, USA ; School of Biology, St. Mary's College Moraga, CA, USA.
Department of Obstetrics, Gynecology and Reproductive Science, UCSF Sandler-Moore Mass Spectrometry Core Facility San Francisco, CA, USA.
Front Microbiol. 2014 Sep 9;5:474. doi: 10.3389/fmicb.2014.00474. eCollection 2014.
Myxococcus xanthus is a bacterial micro-predator known for hunting other microbes in a wolf pack-like manner. Outer membrane vesicles (OMVs) are produced in large quantities by M. xanthus and have a highly organized structure in the extracellular milieu, sometimes occurring in chains that link neighboring cells within a biofilm. OMVs may be a vehicle for mediating wolf pack activity by delivering hydrolytic enzymes and antibiotics aimed at killing prey microbes. Here, both the protein and small molecule cargo of the OMV and membrane fractions of M. xanthus were characterized and compared. Our analysis indicates a number of proteins that are OMV-specific or OMV-enriched, including several with putative hydrolytic function. Secondary metabolite profiling of OMVs identifies 16 molecules, many associated with antibiotic activities. Several hydrolytic enzyme homologs were identified, including the protein encoded by MXAN_3564 (mepA), an M36 protease homolog. Genetic disruption of mepA leads to a significant reduction in extracellular protease activity suggesting MepA is part of the long-predicted (yet to date undetermined) extracellular protease suite of M. xanthus.
粘球菌是一种以狼群方式猎捕其他微生物的细菌微生物掠食者。粘球菌大量产生外膜囊泡（OMV），在细胞外环境中具有高度组织化的结构，有时会以链状形式出现，将生物膜内的相邻细胞连接起来。OMV 可能是通过输送水解酶和抗生素来介导狼群活动的一种媒介，这些酶和抗生素旨在杀死猎物微生物。在这里，我们对粘球菌 OMV 和膜部分的蛋白质和小分子货物进行了表征和比较。我们的分析表明，有许多蛋白质是 OMV 特异性或 OMV 富集的，包括几种具有潜在水解功能的蛋白质。OMV 的次级代谢产物分析鉴定出 16 种分子，其中许多与抗生素活性有关。鉴定出几种水解酶同源物，包括 MXAN_3564（mepA）编码的蛋白，一种 M36 蛋白酶同源物。mepA 的遗传缺失导致细胞外蛋白酶活性显著降低，这表明 MepA 是粘球菌预期的（但迄今为止尚未确定）细胞外蛋白酶组的一部分。
