Modulation of bacterial outer membrane vesicle production by envelope structure and content.
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BACKGROUND: Vesiculation is a ubiquitous secretion process of Gram-negative bacteria, where outer membrane vesicles (OMVs) are small spherical particles on the order of 50 to 250 nm composed of outer membrane (OM) and lumenal periplasmic content. Vesicle functions have been elucidated in some detail, showing their importance in virulence factor secretion, bacterial survival, and biofilm formation in pathogenesis. Furthermore, OMVs serve as an envelope stress response, protecting the secreting bacteria from internal protein misfolding stress, as well as external envelope stressors. Despite their important functional roles very little is known about the regulation and mechanism of vesicle production. Based on the envelope architecture and prior characterization of the hypervesiculation phenotypes for mutants lacking the lipoprotein, Lpp, which is involved in the covalent OM-peptidoglycan (PG) crosslinks, it is expected that an inverse relationship exists between OMV production and PG-crosslinked Lpp. RESULTS: In this study, we found that subtle modifications of PG remodeling and crosslinking modulate OMV production, inversely correlating with bound Lpp levels. However, this inverse relationship was not found in strains in which OMV production is driven by an increase in "periplasmic pressure" resulting from the accumulation of protein, PG fragments, or lipopolysaccharide. In addition, the characterization of an nlpA deletion in backgrounds lacking either Lpp- or OmpA-mediated envelope crosslinks demonstrated a novel role for NlpA in envelope architecture. CONCLUSIONS: From this work, we conclude that OMV production can be driven by distinct Lpp concentration-dependent and Lpp concentration-independent pathways.
SubjectBacterial Outer Membrane Proteins
Escherichia coli Proteins
Published Version (Please cite this version)10.1186/s12866-014-0324-1
Publication InfoKuehn, Margarethe Joanna; Kulp, A; & Schwechheimer, C (2014). Modulation of bacterial outer membrane vesicle production by envelope structure and content. BMC Microbiol, 14. pp. 324. 10.1186/s12866-014-0324-1. Retrieved from http://hdl.handle.net/10161/10654.
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Associate Professor of Biochemistry
Enterotoxigenic E. coli (ETEC) causes traveler's diarrhea and infant mortality in underdeveloped countries, and Pseudomonas aeruginosa is an opportunistic pathogen for immunocompromised patients. Like all gram negative bacteria studied to date, ETEC and P. aeruginosa produce small outer membrane vesicles that can serve as delivery "bombs" to host tissues. Vesicles contain a subset of outer membrane and soluble periplasmic proteins and lipids. In tissues and sera of infected hosts,