An ancestral dual function of OmpM as outer membrane tether and nutrient uptake channel in diderm Firmicutes - Institut Pasteur Accéder directement au contenu
Pré-Publication, Document De Travail Année : 2023

An ancestral dual function of OmpM as outer membrane tether and nutrient uptake channel in diderm Firmicutes

Augustinas Silale
Kahlan Newman
Satya Bhamidimarri
Arnaud Baslé
Syma Khalid

Résumé

The outer membrane (OM) in diderm, or Gram-negative, bacteria must be tethered to peptidoglycan (PG) for mechanical stability and to maintain cell morphology. Most diderm phyla from the Terrabacteria group lack well-characterised OM attachment systems such as Braun’s lipoprotein, Pal and OmpA, but instead have the OmpM protein. OmpM has a periplasmic region containing an S-layer homology domain and a β-barrel region that is embedded in the OM. Here, we have determined the structure of the most abundant OmpM protein from the diderm firmicute Veillonella parvula by single particle cryogenic electron microscopy (cryo-EM). We reveal an OM portion similar to well-characterised trimeric general porins and a mobile periplasmic PG-binding region. Combining the cryo-EM data with crystal structures, structure predictions and molecular dynamics simulations, we show that the periplasmic region of OmpM likely adopts multiple conformations. Single-channel electrophysiology demonstrates ion conductance properties similar to E. coli OmpF. Finally, we demonstrate via functional assays that the four OmpM paralogues are likely to be the only general porins in V. parvula . Together, our results show that OM tethering and nutrient acquisition are genetically linked in V. parvula (and other diderm Firmicutes), suggesting that concurrent loss of two key OM-related functions, tethering and nutrient uptake, promoted the multiple OM loss events that have been inferred in the Terrabacteria.
Fichier principal
Vignette du fichier
Silale_et_al&SuppMat-2023.pdf (7.92 Mo) Télécharger le fichier
Origine : Fichiers produits par l'(les) auteur(s)
Licence : CC BY - Paternité

Dates et versions

pasteur-04252443 , version 1 (20-10-2023)

Licence

Paternité

Identifiants

Citer

Augustinas Silale, Yiling Zhu, Jerzy Witwinowski, Robert Smith, Kahlan Newman, et al.. An ancestral dual function of OmpM as outer membrane tether and nutrient uptake channel in diderm Firmicutes. 2023. ⟨pasteur-04252443⟩

Collections

PASTEUR CNRS ANR
11 Consultations
4 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More