Outer Membrane Vesicle Biosynthesis in Salmonella: Is There More to Gram-Negative Bacteria?

Joachim Reidl

doi:10.1128/mbio.01282-16

Abstract

ABSTRACTRecent research has focused on the biological role of outer membrane vesicles (OMVs), which are derived from the outer membranes (OMs) of Gram-negative bacteria, and their potential exploitation as therapeutics. OMVs have been characterized in many ways and functions. Until recently, research focused on hypothetical and empirical models that addressed the molecular mechanisms of OMV biogenesis, such as vesicles bulging from the OM in various ways. The recently reported study by Elhenawy et al. (mBio 7:e00940-16, 2016, http://dx.doi.org/10.1128/mBio.00940-16) provided further insights into OMV biogenesis of Salmonella enterica serovar Typhimurium. That study showed that deacylation of lipopolysaccharides (LPS) influences the level of OMV production and, furthermore, determines a sorting of high versus low acylated LPS in OMs and OMVs, respectively. Interestingly, deacylation may inversely correlate with other LPS modifications, suggesting some synergy toward optimized host resistance via best OM compositions for S. Typhimurium.

Highlights

Little attention was paid to bacterium-derived membrane vesicles (MVs) until the last few decades
The recent study by Elhenawy et al [12] contributes significantly to our understanding of outer membrane vesicles (OMVs) biogenesis by showing that mainly deacylated LPS are found in OMVs
Typhimurium propagating in a J774A.1 macrophage cell culture and compared the OMV level produced by a pagL knockout mutant versus that of the wild type

Summary

Introduction

Little attention was paid to bacterium-derived membrane vesicles (MVs) until the last few decades. The recent study by Elhenawy et al [12] contributes significantly to our understanding of OMV biogenesis by showing that mainly deacylated LPS are found in OMVs. This implies that some sorting mechanisms exist to distinguish LPS molecules based on the content of acyl residues contained on the GlucNAc backbone of the lipid A moiety. Elhenawy et al analyzed the lipid A content of the OMs and OMVs in a pagL mutant which lacked the gene for a PhoPQ-regulated lipid A lipase enzyme and which showed no difference from the wild type in its LPS profile.

Results

Conclusion