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1.
FIG. 2.

FIG. 2. From: Functional Analysis of the Protein Machinery Required for Transport of Lipopolysaccharide to the Outer Membrane of Escherichia coli .

Cell morphology upon depletion of LptA-LptB, LptE, LptD, and LptC. Cells grown in the presence (+) or in the absence (−) of arabinose were prepared for electron microscopy as described in Materials and Methods. Scale bars, 0.5 μm.

Paola Sperandeo, et al. J Bacteriol. 2008 July;190(13):4460-4469.
2.
FIG. 1.

FIG. 1. From: Functional Analysis of the Protein Machinery Required for Transport of Lipopolysaccharide to the Outer Membrane of Escherichia coli .

Subcellular localization of LptC. BW25113/pGS108 cells were induced with IPTG, disrupted, and fractionated as described in Materials and Methods. Samples of periplasmic (P), cytoplasmic (S), IM, and OM fractions were analyzed by SDS-PAGE and Western blotting with anti-His6 antibodies (upper panel). The same fractions were analyzed with anti-YidC antibodies as an IM marker (lower panel). T, total protein fraction.

Paola Sperandeo, et al. J Bacteriol. 2008 July;190(13):4460-4469.
3.
FIG. 5.

FIG. 5. From: Functional Analysis of the Protein Machinery Required for Transport of Lipopolysaccharide to the Outer Membrane of Escherichia coli .

WaaL dependence of anomalous LPS production. The strains carrying a functional O-antigen ligase (+ waaL) or in which the O-antigen ligase is disrupted (− waaL) were grown with arabinose (+ ara) or without arabinose (− ara) as described in Material and Methods. The LPS profile was determined by Western blotting using anti-LPS WN1 222-5 antibodies. (A) LptE depletion, 300 min. (B) LptD depletion, 360 min. (C) LptAB depletion, 240 min. (D) LptC depletion, 360 min.

Paola Sperandeo, et al. J Bacteriol. 2008 July;190(13):4460-4469.
4.
FIG. 6.

FIG. 6. From: Functional Analysis of the Protein Machinery Required for Transport of Lipopolysaccharide to the Outer Membrane of Escherichia coli .

Model for the transport of LPS. The lipid A-core moiety is synthesized in the cytoplasm and flipped over the IM by MsbA. LptA, LptB, and LptC are part of a protein machine that transports LPS across the periplasm to the OM. The two additional transmembrane components recently identified (31), LptF and LptG, are postulated to complete the IM-bound ABC transporter. The LptD/LptE complex is thought to mediate the insertion of the newcomer LPS into the OM. The former names of the proteins are indicated in parentheses.

Paola Sperandeo, et al. J Bacteriol. 2008 July;190(13):4460-4469.
5.
FIG. 4.

FIG. 4. From: Functional Analysis of the Protein Machinery Required for Transport of Lipopolysaccharide to the Outer Membrane of Escherichia coli .

(a) MALDI-MS spectrum of the product OS1. The main molecular ion at m/z 1796.7 consists either of hexa-acylated lipid A or the complete core region of wild-type E. coli K-12 LPS, whereas the higher-molecular-mass ion peaks can be assigned to the same oligosaccharide that in addition bears one or more bis-acetylated colanic acid repeating units (Δm/z 1038) lacking a pyruvate group. (b) 1H NMR spectrum of the O-deacetylated OS1 product, in which the great heterogeneity of the sample due to nonstoichiometric substitutions and reducing KDO arrangements is evident. (Inset) Anomeric assignments of the colanic acid single repeating unit as shown in Table S1 in the supplemental material. (c) Repeating unit of colanic acid. Residues are α-configured unless stated otherwise.

Paola Sperandeo, et al. J Bacteriol. 2008 July;190(13):4460-4469.
6.
FIG. 3.

FIG. 3. From: Functional Analysis of the Protein Machinery Required for Transport of Lipopolysaccharide to the Outer Membrane of Escherichia coli .

Membrane fractionation of cells depleted of LptA-LptB, LptD, LptE, and LptC. FL907, AM661, AM689, and FL905 cultures were grown with arabinose to an OD600 of 0.2, harvested, and resuspended in an arabinose-supplemented or arabinose-free medium. About 1 h after the cultures had reached the maximal OD600 (OD600 between 0.2 and 0.6), cells were pulse-labeled for 2 min with [3H]GlnNAc and chased for 5 min with 0.4% nonradioactive GlnNAc; the nondepleted cultures were pulse-labeled when the same OD600 was reached, as described in Materials and Methods. Total membranes prepared from cells were fractionated by sucrose density gradient. Fractions were collected from the top of the gradient and immunoblotted using antibodies recognizing LPS, LamB, and a 55-kDa IM protein as indicated. Fractions were also analyzed for total incorporated radioactivity. The panels on the left show the percentages of the total incorporated radioactivity for nondepleted (▪) and depleted (○) mutant cells. The panels on the right show the LamB and OmpA profiles of nondepleted (+ ara) and depleted (− ara) mutant cells. The OmpA protein cross-reacts with the LamB antibody. (A) FL907 cells depleted and not depleted of LptA-LptB. (B) AM661 cells depleted and not depleted of LptD. (C) AM689 cells depleted and not depleted of LptE. (D) FL905 cells depleted and not depleted of LptC.

Paola Sperandeo, et al. J Bacteriol. 2008 July;190(13):4460-4469.

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