Project description:The antibiotic fosfomycin is widely recognized for treatment of lower urinary tract infections caused by Escherichia coli and lately gained importance as a therapeutic option to combat multidrug resistant bacteria. Still, resistance to fosfomycin frequently develops through mutations reducing its uptake. Whereas the inner membrane transport of fosfomycin has been extensively studied in E. coli, its outer membrane (OM) transport remains insufficiently understood. While evaluating minimal inhibitory concentrations in OM porin-deficient mutants, we observed that the E. coli ΔompCΔompF strain is five times more resistant to fosfomycin than the wild type and the respective single mutants. Continuous monitoring of cell lysis of porin-deficient strains in response to fosfomycin additionally indicated the relevance of LamB. Furthermore, the physiological relevance of OmpF, OmpC and LamB for fosfomycin uptake was confirmed by electrophysiological and transcriptional analysis. This study expands the knowledge of how fosfomycin crosses the OM of E. coli.
Project description:Carbapenem-resistant Acinetobacter baumannii (CRAB) is a critical nosocomial pathogen with limited treatment options. Although antibiotic resistance in CRAB is well-characterized, its interactions with host immunity and the contribution of outer membrane vesicles (OMVs) to pathogenesis remain poorly understood. We examined a clinical CRAB isolate and compared it with the reference strain A19606. Antimicrobial susceptibility testing revealed complete resistance of CRAB to commonly used antibiotics in clinical practice, while A19606 remained susceptible to most agents. In murine intranasal infection models and bone marrow-derived macrophages, CRAB induced significantly stronger activation of inflammatory signaling pathways and elevated levels of pro-inflammatory cytokines relative to A19606. Transcriptomic analysis of infected lung tissue identified differentially expressed genes, enriched for inflammatory response pathways. proteomics showed upregulated proteins in CRAB related to secretion systems. OMVs characterization revealed that CRAB-derived OMVs highly enriched in proteins associated with periplasmic and outer membrane spaces, and more potent in triggering macrophage inflammatory signaling. CRAB displays expansive antibiotic resistance and enhanced pro-inflammatory potential mediated in part by unique OMVs properties. Targeting OMVs formation or host immune modulation may represent effective strategies for combating CRAB infections.
Project description:The rise of antimicrobial resistant pathogens calls for new antibacterial treatments, but potent new compounds are scarce. Development of new antibiotics is difficult, especially against Gram-negative bacteria, as here uptake is strongly hindered by the additional outer membrane. Most antimicrobial agents against Gram-negatives use the porin mediated pathway to cross the outer membrane, which limits the choice of an antibiotic, as it has to fit by size, charge and hydrophilicity. In E. coli, the major porins OmpF and OmpC are associated with antibiotic translocation and therefore also with unspecific antibiotic cross-resistance. In this regard, alternative uptake routes are of interest. We were interested in the uptake opportunities of the small, natural product antibiotic negamycin and thereby found new uptake pathways across the outer membrane of E. coli. Besides OmpF and OmpC, we investigated the role of the minor porins OmpN and ChiP in negamycin translocation. We detected an effect of OmpN and ChiP on negamycin susceptibility and confirmed passage by electrophysiological assays. The structure of OmpN was resolved in order to analyze the negamycin translocation mechanism by computational simulations. As abundancy of these minor porins was low in E. coli, their transcript levels were analyzed by RNA-Seq. Increased transcripts levels of ompN and chiP were observed upon negamycin treatment, hinting at a role in antibiotic uptake. These new, additional uptake pathways across the outer membrane of E. coli highlight the antibiotic potential of negamycin, especially as resistance development is low due to availability of multiple uptake routes at both the outer and inner membranes
Project description:We performed comparative transcriptomic analysis of the outer membrane vesicles (OMVs) released from B. burgdorferi. We identified a total of ~1200 unique transcripts with at least one mapped read from the bacterial cell and its OMVs.
Project description:Uropathogenic bacteria present a variety of mechanisms that allow them to colonize the urinary tract. These mechanisms include biofilm formation, urothelial cell invasion, and the production of adhesins, toxins, and siderophores. Uropathogenic Escherichia coli and Proteus mirabilis are two of the most common etiological agents causing urinary tract infections (UTI). In addition to virulence factors, Gram-negative bacteria can produce outer membrane vesicles (OMVs). The OMVs may have several functions in the context of UTI. In the present work, we isolated and characterized OMVs from two clinical strains: E. coli U144 and P. mirabilis 2921 cultured in Luria-Bertani broth and artificial urine. The OMVs were examined using DLS, NTA and TEM and found to be between 85 and 260 nm in size, the largest being those obtained in artificial urine. All OMVs had a low polydispersity factor and negative charge in their surface. Through proteomic analysis (nanoLC-MS/MS), 282 and 353 proteins were identified in OMVs obtained from E. coli and P. mirabilis LB cultures respectively, and 215 and 103 proteins when they were grown in AU. The majority of proteins were from the bacterial envelope. Also, several proteins related to motility and adhesion were found. The composition of OMVs proteins was different according to the culture medium. Among the identified proteins, those related with zinc and iron uptake systems could have an important role in AU. These results bring us closer to understanding the possible role of OMVs in the pathogenesis of UTIs.
Project description:Large-scale production of bacterial extracellular vesicles is a hurdle for their development as novel cancer immunotherapeutic agents. Here, we developed manufacturing processes for mass production of Escherichia coli EVs known as outer membrane vesicles (OMVs). We present a comprehensive proteome of mass-produced E. coli OMVs.
Project description:Asthma is the most common chronic respiratory disease. Asthma that cannot be well controlled by steroid treatment is called steroid-resistant asthma. Steroid-resistant asthma accounts for only 5% of all asthma cases, but it accounts for 80% of asthma healthcare costs. Nontypeable Haemophilus influenzae (NTHi), as a Gram-negative bacterium, can release outer membrane vesicles (OMVs) and transfer biomolecules to host cells and the external environment by carrying lipopolysaccharides, proteins, peptidoglycans, outer membrane proteins, cell wall components, proteins, nucleic acids, ion metabolites, and signaling molecules. Thus, it plays a role in obtaining nutrition, stress, toxin delivery, adhesion, host immune surveillance evasion, and host immune response regulation. It becomes an essential way in bacterial pathogenesis. To further clarify whether NTHi OMVs could be inhaled to induce steroid-resistant asthma, we isolated and purified NTHi OMVs. In vivo experiments showed that NTHi OMVs could be inhaled and enter airway epithelial cells. Cosensitization with OVA induces steroid-resistant asthma in mice. Furthermore, through high-throughput sequencing, we found that the NTHi OMVs and OVA co-sensitized mice had significantly enriched inflammatory and immune-related signaling pathways, and the transcription and secretion of IL-1β were increased was the potential cause of SRA.
Project description:Characterization of the sRNA content of P. aeruginosa OMVs compared to whole cells. Result: OMVs contain differentially packaged sRNAs. Whole cell PA14 and OMVs from 3 separate preparations.
Project description:Vibrio cholerae is highly motile by the action of a single polar flagellum. The loss of motility reduces the infectivity of V. cholerae, demonstrating that motility is an important virulence factor. FlrC is the sigma-54-dependent positive regulator of flagellar genes. Recently, the genes VC2206 (flgP) and VC2207 (flgO) were identified as being regulated by FlrC by microarray analysis of an flrC mutant. FlgP is reported to be an outer membrane lipoprotein required for motility that functions as a colonization factor. The study reported here focuses on the characterization of flgO, the first gene in the flgOP operon. We show FlgO/P are important for motility, as these mutants have reduced motility phenotypes. The flgO/P mutant populations display fewer motile cells as well as reduced numbers of flagellated cells. The flagella produced by the flgO/P mutant strains are shorter in length than the WT flagella, which can be restored by inhibiting rotation of the flagellum. FlgO is an outer membrane protein that localizes throughout the membrane and not at the flagellar pole. Although FlgO/P do not specifically localize to the flagellum, they are required for flagellar stability. Due to the nature of these motility defects, we established that the flagellum is not sufficient for adherence, rather, motility is the essential factor required for attachment and thus colonization by V. cholerae O1 of the classical biotype. This study reveals a novel mechanism for which the OMPs FlgO and FlgP function in motility to mediate flagellar stability and influence attachment and colonization. Vibrio cholerae O395 vs. rpoN mutant