Dataset Information

The bacterial outer membrane ?-barrel assembly machinery.

ABSTRACT: ?-Barrel proteins found in the outer membrane of Gram-negative bacteria serve a variety of cellular functions. Proper folding and assembly of these proteins are essential for the viability of bacteria and can also play an important role in virulence. The ?-barrel assembly machinery (BAM) complex, which is responsible for the proper assembly of ?-barrels into the outer membrane of Gram-negative bacteria, has been the focus of many recent studies. This review summarizes the significant progress that has been made toward understanding the structure and function of the bacterial BAM complex.

SUBMITTER: Kim KH

PROVIDER: S-EPMC3403412 | biostudies-literature | 2012 Jun

REPOSITORIES: biostudies-literature

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Publications

The bacterial outer membrane β-barrel assembly machinery.

Kim Kelly H KH Aulakh Suraaj S Paetzel Mark M

Protein science : a publication of the Protein Society 20120501 6

β-Barrel proteins found in the outer membrane of Gram-negative bacteria serve a variety of cellular functions. Proper folding and assembly of these proteins are essential for the viability of bacteria and can also play an important role in virulence. The β-barrel assembly machinery (BAM) complex, which is responsible for the proper assembly of β-barrels into the outer membrane of Gram-negative bacteria, has been the focus of many recent studies. This review summarizes the significant progress th ...[more]

PMID: 22549918

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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

The bacterial outer membrane ?-barrel assembly machinery.

Publications

The bacterial outer membrane β-barrel assembly machinery.

Similar Datasets

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