Inoue Hiromu, Kawano Kenichi, Kawamoto Jun, Ogawa Takuya, Kurihara Tatsuo
Institute for Chemical Research, Kyoto University, Uji, Kyoto, Japan.
Graduate School of Pharmaceutical Sciences, Kyoto University, Kyoto, Japan.
J Bacteriol. 2025 May 22;207(5):e0049724. doi: 10.1128/jb.00497-24. Epub 2025 Apr 4.
Bacteria secrete extracellular membrane vesicles (EMVs). Physiological functions and biotechnological applications of these lipid nanoparticles have been attracting significant attention. However, the details of the molecular basis of EMV biogenesis have not yet been fully elucidated. In our previous work, an N-terminus-substituted FAAV peptide labeled with nitrobenzoxadiazole (NBD; nFAAV5-NBD) was developed. This peptide can sense the curvature of a lipid bilayer and selectively bind to EMVs even in the presence of cells. Here, we applied nFAAV5-NBD to a genome-wide screening of hyper- and hypo-vesiculation transposon mutants of a Gram-negative bacterium, HM13, to identify the genes involved in EMV production. We analyzed the transposon insertion sites in hyper- and hypo-vesiculation mutants and identified 16 and six genes, respectively, with a transposon inserted within or near them. Targeted gene-disrupted mutants of the identified genes showed that the lack of putative dipeptidyl carboxypeptidase, glutamate synthase β-subunit, LapG protease, metallohydrolase, RNA polymerase sigma-54 factor, inactive transglutaminase, PepSY domain-containing protein, and Rhs-family protein caused EMV overproduction. On the other hand, disruption of the genes encoding putative phosphoenolpyruvate synthase, d-hexose-6-phosphate epimerase, NAD-specific glutamate dehydrogenase, and sensory box histidine kinase/response regulator decreased EMV production. This study demonstrates the utility of a novel screening method using a curvature-sensing peptide for mutants with altered EMV productivity and provides information on the genes related to EMV production.IMPORTANCEConventional methods for isolation and quantification of extracellular membrane vesicles (EMVs) are generally time-consuming. nFAAV5-NBD can detect EMVs in the culture without separating EMVs from cells. detection of EMVs using this peptide facilitated screening of the genes related to EMV production. We succeeded in identifying various genes associated with EMV production of HM13, which would contribute to the elucidation of bacterial EMV formation mechanisms. Additionally, the hyper-vesiculating mutants obtained in this study would be valuable for EMV applications, such as secreting useful substances as EMV cargoes and producing artificially functionalized EMVs.
细菌分泌细胞外膜泡(EMV)。这些脂质纳米颗粒的生理功能和生物技术应用一直备受关注。然而,EMV生物发生的分子基础细节尚未完全阐明。在我们之前的工作中,开发了一种用硝基苯并恶二唑(NBD;nFAAV5-NBD)标记的N端取代的FAAV肽。这种肽可以感知脂质双层的曲率,即使在有细胞存在的情况下也能选择性地与EMV结合。在这里,我们将nFAAV5-NBD应用于革兰氏阴性菌HM13的超囊泡化和低囊泡化转座子突变体的全基因组筛选,以鉴定参与EMV产生的基因。我们分析了超囊泡化和低囊泡化突变体中的转座子插入位点,分别鉴定出16个和6个基因,其内部或附近插入了转座子。对鉴定出的基因进行靶向基因敲除突变体分析表明,假定的二肽基羧肽酶、谷氨酸合酶β亚基、LapG蛋白酶、金属水解酶、RNA聚合酶σ-54因子、无活性转谷氨酰胺酶、含PepSY结构域的蛋白和Rhs家族蛋白的缺失导致EMV过量产生。另一方面,编码假定的磷酸烯醇丙酮酸合酶、D-己糖-6-磷酸差向异构酶、NAD特异性谷氨酸脱氢酶和传感盒组氨酸激酶/应答调节因子的基因的破坏降低了EMV的产生。这项研究证明了使用曲率感应肽对EMV生产力改变的突变体进行新型筛选方法的实用性,并提供了与EMV产生相关的基因信息。重要性传统的细胞外膜泡(EMV)分离和定量方法通常很耗时。nFAAV5-NBD可以在不将EMV与细胞分离的情况下检测培养物中的EMV。使用这种肽检测EMV有助于筛选与EMV产生相关的基因。我们成功地鉴定了与HM13的EMV产生相关的各种基因,这将有助于阐明细菌EMV形成机制。此外,本研究中获得的超囊泡化突变体对于EMV应用将是有价值的,例如作为EMV货物分泌有用物质和生产人工功能化的EMV。