Dataset Information

Alteration of Membrane Fluidity or Phospholipid Composition Perturbs Rotation of MreB Complexes in Escherichia coli.

ABSTRACT: Gram-negative bacteria such as Escherichia coli are surrounded by inner and outer membranes and peptidoglycan in between, protecting the cells from turgor pressure and maintaining cell shape. The Rod complex, which synthesizes peptidoglycan, is composed of various proteins such as a cytoplasmic protein MreB, a transmembrane protein RodZ, and a transpeptidase PBP2. The Rod complex is a highly motile complex that rotates around the long axis of a cell. Previously, we had reported that anionic phospholipids (aPLs; phosphatidylglycerol and cardiolipin) play a role in the localization of MreB. In this study, we identified that cells lacking aPLs slow down Rod complex movement. We also found that at higher temperatures, the speed of movement increased in cells lacking aPLs, suggesting that membrane fluidity is important for movement. Consistent with this idea, Rod complex motion was reduced, and complex formation was disturbed in the cells depleted of FabA or FabB, which are essential for unsaturated fatty acid synthesis. These cells also showed abnormal morphology. Therefore, membrane fluidity is important for maintaining cell shape through the regulation of Rod complex formation and motility.

SUBMITTER: Kurita K

PROVIDER: S-EPMC7719821 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature

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Publications

Alteration of Membrane Fluidity or Phospholipid Composition Perturbs Rotation of MreB Complexes in <i>Escherichia coli</i>.

Kurita Keisuke K Kato Fumiya F Shiomi Daisuke D

Frontiers in molecular biosciences 20201124

Gram-negative bacteria such as <i>Escherichia coli</i> are surrounded by inner and outer membranes and peptidoglycan in between, protecting the cells from turgor pressure and maintaining cell shape. The Rod complex, which synthesizes peptidoglycan, is composed of various proteins such as a cytoplasmic protein MreB, a transmembrane protein RodZ, and a transpeptidase PBP2. The Rod complex is a highly motile complex that rotates around the long axis of a cell. Previously, we had reported that anion ...[more]

PMID: 33330621

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Project description:Integral ?-barrel membrane proteins are folded and inserted into the Gram-negative bacterial outer membrane by the ?-barrel assembly machine (BAM). This essential complex, composed of a ?-barrel protein, BamA, and four lipoproteins, BamB, BamC, BamD, and BamE, resides in the outer membrane, a unique asymmetrical lipid bilayer that is difficult to recapitulate in vitro Thus, the probing of BAM function in living cells is critical to fully understand the mechanism of ?-barrel folding. We recently identified an anti-BamA monoclonal antibody, MAB1, that is a specific and potent inhibitor of BamA function. Here, we show that the inhibitory effect of MAB1 is enhanced when BAM function is perturbed by either lowering the level of BamA or removing the nonessential BAM lipoproteins, BamB, BamC, or BamE. The disruption of BAM reduces BamA activity, increases outer membrane (OM) fluidity, and activates the ?E stress response, suggesting the OM environment and BAM function are interconnected. Consistent with this idea, an increase in the membrane fluidity through changes in the growth environment or alterations to the lipopolysaccharide in the outer membrane is sufficient to provide resistance to MAB1 and enable the BAM to tolerate these perturbations. Amino acid substitutions in BamA at positions in the outer membrane spanning region or the periplasmic space remote from the extracellular MAB1 binding site also provide resistance to the inhibitory antibody. Our data highlight that the outer membrane environment is a critical determinant in the efficient and productive folding of ?-barrel membrane proteins by BamA.IMPORTANCE BamA is an essential component of the ?-barrel assembly machine (BAM) in the outer membranes of Gram-negative bacteria. We have used a recently described inhibitory anti-BamA antibody, MAB1, to identify the molecular requirements for BAM function. Resistance to this antibody can be achieved through changes to the outer membrane or by amino acid substitutions in BamA that allosterically affect the response to MAB1. Sensitivity to MAB1 is achieved by perturbing BAM function. By using MAB1 activity and functional assays as proxies for BAM function, we link outer membrane fluidity to BamA activity, demonstrating that an increase in membrane fluidity sensitizes the cells to BAM perturbations. Thus, the search for potential inhibitors of BamA function must consider the membrane environment in which ?-barrel folding occurs.

Dataset Information

Alteration of Membrane Fluidity or Phospholipid Composition Perturbs Rotation of MreB Complexes in Escherichia coli.

Publications

Alteration of Membrane Fluidity or Phospholipid Composition Perturbs Rotation of MreB Complexes in <i>Escherichia coli</i>.

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