Biophysical, proteomic, and lipidomic characterization of Streptococcus mutans extracellular membrane vesicles from wild-type, ΔsrtA, and Δsfp strains provides novel information regarding vesiculogenesis and its function

ABSTRACT: Extracellular membrane vesicles (EMVs) are produced by many Gram-positive organisms, but information regarding vesiculogenesis is largely unknown. In this study, we isolated and characterized EMVs derived from the oral pathogen Streptococcus mutans and two deletion mutants, ΔsrtA and Δsfp. ΔsrtA EMVs were notably enlarged, and the AtlA autolysin was unprocessed in this strain. EMVs from all strains contained proteins involved in cell wall biogenesis and cell architecture, bacterial adhesion, biofilm cell density and matrix development, and intermolecular competition with other microorganisms. Proteomic and lipidomic analyses showed that vesicular and cytoplasmic membranes are dissimilar in many respects. A higher proportion of vesicular proteins are transported by the general secretion pathway, with SecA identified as a prominent EMV component. In contrast, cytoplasmic membranes were over-represented in multi-pass transmembrane protein substrates of co-translational transport machineries. EMVs from the wild-type (WT), but not the mutant strains, were enriched in cardiolipin compared to the cytoplasmic membrane, and all EMVs were over-represented in polyketides and flavonoids. Both vesicular and cytoplasmic membranes were rich in long-chain fatty acids, including saturated, monounsaturated, and polyunsaturated, except for Δsfp EMVs that contained exclusively polyunsaturated fatty acids. Lipoproteins were less prevalent in EMVs of all three strains compared to their cytoplasmic membranes. This study provides insight into biophysical characteristics of S. mutans EMVs and indicates discrete partitioning of protein and lipid components between EMVs and corresponding cytoplasmic membranes of both WT and mutant strains.

INSTRUMENT(S): Q Exactive HF

ORGANISM(S): Streptococcus Mutans Serotype C

TISSUE(S): Protoplast, Extracellular Vesicle

SUBMITTER: Joyce Morales Aparicio  

LAB HEAD: L. Jeannine Brady

PROVIDER: PXD019825 | Pride | 2020-11-17

REPOSITORIES: Pride