Timing of TolA and TolQ Recruitment at the Septum Depends on the Functionality of the Tol-Pal System

BACCELLI, Pauline; Rachedi, Raphaël; Serrano, Bastien; Petiti, Mélissa; Bernard, Christophe; Houot, Laetitia; Duché, Denis

doi:10.1016/j.jmb.2022.167519

Cited by 4 publications

(2 citation statements)

References 42 publications

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“…Regardless of the molecular mechanism, however, the main function of the Tol-Pal complex in OM lipid homeostasis is likely also beneficial for OM invagination during cell division. After all, the IM components TolQ, TolR, and TolA are recruited to the septum via at least two independent ways linked to septal cell wall biosynthesis (34, 39, 56), indicating a possible evolutionary advantage for Tol-Pal function(s) to exist at mid-cell. While Pal-mediated tethering of the OM to the cell wall should contribute to septal OM invagination, we propose that changing lipid composition, i.e.…”

Section: Discussionmentioning

confidence: 99%

Primary role of the Tol-Pal complex in bacterial outer membrane lipid homeostasis

Tan,

Chng

2024

Preprint

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Gram-negative bacteria are defined by an outer membrane (OM) that contributes to cell envelope integrity, and functions as an effective permeability barrier. The OM is thus critical for fitness and antibiotic resistance. Building this bilayer require proper assembly of lipopolysaccharides, proteins, and phospholipids, yet how the intricate balance of these components is achieved to ensure a stable OM is not well understood. One system long known to be important for OM stability is the Tol-Pal complex, which has recently been implicated in the maintenance of OM lipid homeostasis, possibly via retrograde phospholipid transport. However, assignment of its primary function has been challenging, owing to septal localization of Tol-Pal and its associated role(s) during cell division. Here, we uncouple the function of the Tol-Pal complex in OM lipid homeostasis from its impact on cell division inEscherichia coli, by preventing recruitment to mid-cell. The Tol-Pal complex comprises the inner membrane TolQRA and OM TolB-Pal subcomplexes. We engineer a TolA variant that forms a chimeric complex with ExbBD, which are homologous to TolQR, resulting in loss of septal enrichment of Tol-Pal. We demonstrate that this peripherally-localized complex cannot rescue division defects in strains lacking TolQRA, but restores OM integrity and barrier. Importantly, this chimeric complex is fully capable of maintaining lipid balance in the OM, independent of the role of Tol-Pal in cell division. Our work establishes the primary function of the Tol-Pal complex in OM lipid homeostasis, and provides novel insights on how this conserved system also contributes to cell division.

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Section: Discussionmentioning

confidence: 99%

Primary role of the Tol-Pal complex in bacterial outer membrane lipid homeostasis

Tan,

Chng

2024

Preprint

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“…In E. coli , mutants of the Tol–Pal system display numerous defects collectively called tol phenotypes, such as a chaining morphology in low osmotic medium, hypersensitivity to detergents, resistance to Tol-dependent toxins called colicins ( 37 ), and increased resistance to chromate ( 38 ). Thorough analysis of these pleiotropic phenotypes over the past 50 years demonstrated that the Tol–Pal complex is crucial in envelope integrity maintenance, OM lipid homeostasis, and in the late stage of cell division ( 39 , 40 , 41 , 42 , 43 ).…”

mentioning

confidence: 99%

Direct interaction between fd phage pilot protein pIII and the TolQ–TolR proton-dependent motor provides new insights into the import of filamentous phages

Pellegri¹,

Moreau²,

Duché³

et al. 2023

Journal of Biological Chemistry

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The structure of the OmpA/Pal protein ofAnaplasma phagocytophilum

Cadby

2023

Preprint

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Peptidoglycan associated lipoprotein (Pal) contributes to cell division in many Gram-negative bacteria via its interactions with the outer membrane, peptidoglycan, and other periplasmic proteins. Intriguingly, Pal and Outer Membrane Protein A (OmpA), which also interacts with the outer membrane and peptidoglycan, have moonlighting roles as virulence factors and facilitate infection and/or host-pathogen interactions in a range of bacteria. The Pal family protein of Anaplasma phagocytophilum, which is a tick-borne pathogen that infects a wide range of hosts, seems to function primarily as a virulence factor, since this bacterium lacks a peptidoglycan cell wall. Here we present crystal structures of the Pal protein of A. phagocytophilum (commonly referred to as an OmpA protein), demonstrating that this protein has amino acid insertions that confer flexibility and that this insertion is also found in the Pal proteins of some related bacteria, which are also pathogens. Whether this flexibility is reflective of any adaptations for host-pathogen interactions remains to be determined.

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Timing of TolA and TolQ Recruitment at the Septum Depends on the Functionality of the Tol-Pal System

Cited by 4 publications

References 42 publications

Primary role of the Tol-Pal complex in bacterial outer membrane lipid homeostasis

Primary role of the Tol-Pal complex in bacterial outer membrane lipid homeostasis

Direct interaction between fd phage pilot protein pIII and the TolQ–TolR proton-dependent motor provides new insights into the import of filamentous phages

The structure of the OmpA/Pal protein ofAnaplasma phagocytophilum

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