Department of Molecular Biology, The Laboratory for Molecular Infection Medicine Sweden (MIMS), Umeå University, Umeå, Sweden.
PLoS Pathog. 2013;9(10):e1003620. doi: 10.1371/journal.ppat.1003620. Epub 2013 Oct 3.
Outer membrane vesicles (OMVs) that are released from Gram-negative pathogenic bacteria can serve as vehicles for the translocation of effectors involved in infectious processes. In this study we have investigated the role of OMVs of the Vibrio cholerae O1 El Tor A1552 strain in resistance to antimicrobial peptides (AMPs). To assess this potential role, we grew V. cholerae with sub-lethal concentrations of Polymyxin B (PmB) or the AMP LL-37 and analyzed the OMVs produced and their effects on AMP resistance. Our results show that growing V. cholerae in the presence of AMPs modifies the protein content of the OMVs. In the presence of PmB, bacteria release OMVs that are larger in size and contain a biofilm-associated extracellular matrix protein (Bap1). We demonstrated that Bap1 binds to the OmpT porin on the OMVs through the LDV domain of OmpT. In addition, OMVs from cultures incubated in presence of PmB also provide better protection for V. cholerae against LL-37 compared to OMVs from V. cholerae cultures grown without AMPs or in presence of LL-37. Using a bap1 mutant we showed that cross-resistance between PmB and LL-37 involved the Bap1 protein, whereby Bap1 on OMVs traps LL-37 with no subsequent degradation of the AMP.
外膜囊泡（OMVs）是革兰氏阴性致病菌释放的，可以作为感染过程中效应因子转运的载体。在本研究中，我们研究了霍乱弧菌 O1 El Tor A1552 株 OMVs 在抗抗菌肽（AMPs）中的作用。为了评估这种潜在的作用，我们用亚致死浓度的多粘菌素 B（PmB）或 AMP LL-37 培养霍乱弧菌，并分析了产生的 OMVs 及其对 AMP 耐药性的影响。结果表明，在 AMP 存在的情况下培养霍乱弧菌会改变 OMVs 的蛋白含量。在 PmB 的存在下，细菌释放的 OMVs 尺寸更大，并且含有生物膜相关的细胞外基质蛋白（Bap1）。我们证明 Bap1 通过 OmpT 的 LDV 结构域与 OMVs 上的 OmpT 孔蛋白结合。此外，与没有 AMP 或存在 LL-37 的霍乱弧菌培养物相比，在 PmB 存在下培养的 OMVs 还能更好地保护霍乱弧菌免受 LL-37 的侵害。使用 bap1 突变体，我们表明 PmB 和 LL-37 之间的交叉耐药性涉及 Bap1 蛋白，Bap1 蛋白在 OMVs 上捕获 LL-37 而不随后降解 AMP。
