gram negative

Edge evidence

• outer membrane defines gram negative METPO:2007500

  The outer membrane is a defining feature of the Gram-negative cell envelope.

  • DOI:10.1038/s41579-019-0201-x defining feature of the Gram-negative cell envelope Supports outer membrane as the key Gram-negative envelope feature.
• lipopolysaccharide localized in outer membrane biolink:located_in

  LPS is found on the outer surface of the Gram-negative outer membrane.

  • DOI:10.1038/s41579-019-0201-x lipopolysaccharide exclusively found on the surface Supports LPS as a surface-exposed outer-membrane component.
• thin peptidoglycan layer localized in periplasmic space biolink:located_in

  Gram-negative peptidoglycan is a thin layer in the periplasm.

  • DOI:10.1016/j.bbalip.2016.10.010 periplasm ... containing a thin layer of peptidoglycan Supports thin periplasmic peptidoglycan in Gram-negative envelopes.
• thin peptidoglycan layer fails to retain crystal violet-iodine complex

  Thin peptidoglycan and outer-membrane disruption allow dye complex loss during decolorization.

  • DOI:10.3109/10520299609117151 cell wall ... responsible for retention Inference from Gram-positive retention mechanism; thinner Gram-negative peptidoglycan contributes to non-retention.
• counterstain produces gram negative METPO:2000202

  Counterstain gives decolorized Gram-negative cells their pink/red appearance.

  • DOI:10.3109/10520299609117151 mechanism of the Gram stain Supports Gram stain procedure context; counterstain appearance follows dye-complex loss.
• lipopolysaccharide occupies outer membrane outer leaflet

  LPS occupies the outer leaflet of the Gram-negative outer membrane (OM asymmetry).

  • DOI:10.1146/annurev-micro-032521-014507 LPS occupies the outer leaflet while phospholipids occupy the inner leaflet.
• divalent cations (Mg2+/Ca2+) stabilizes lipopolysaccharide

  Divalent cations (Mg2+/Ca2+) stabilize LPS packing in the OM outer leaflet.

  • DOI:10.3390/pathogens13100889 Divalent cations (Mg2+/Ca2+) stabilize LPS packing.
• lipopolysaccharide contributes to outer membrane barrier function RO:0002326

  Tight LPS packing with OM proteins creates the impermeable OM barrier.

  • DOI:10.1146/annurev-micro-032521-014507 The tight packing of LPS and OM proteins creates an impermeable barrier.
• Lpt pathway transports lipopolysaccharide METPO:2000207

  The Lpt machinery transports LPS across the periplasm for insertion into the OM.

  • DOI:10.1007/s12275-024-00137-w LPS transported to the OM by the ATP-driven Lpt machinery; moves LPS across periplasm for OM insertion.
• BAM complex inserts beta-barrel outer membrane proteins

  The BAM complex folds and inserts beta-barrel OMPs into the outer membrane.

  • DOI:10.3390/pathogens13100889 The Bam complex (BamA-E) folds uOMPs into beta-barrels.
• Mla pathway maintains outer membrane lipid asymmetry

  The Mla pathway counteracts phospholipid flipping to maintain OM lipid asymmetry.

  • DOI:10.3390/pathogens13100889 Mla system performs retrograde transport to counteract PL flipping to the outer leaflet.
• Tol-Pal system safeguards cell envelope connectivity

  Tol-Pal safeguards connectivity between the three layers of the Gram-negative envelope.

  • DOI:10.1038/s44259-024-00065-0 Tol-Pal safeguards connectivity between the three layers of the Gram-negative cell envelope.