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Reinforcing Lipid A Acylation on the Cell Surface of Acinetobacter baumannii Promotes Cationic Antimicrobial Peptide Resistance and Desiccation Survival.

Boll JM, Tucker AT, Klein DR, Beltran AM, Brodbelt JS, Davies BW, Trent MS - MBio (2015)

Bottom Line: Acinetobacter baumannii is an emerging Gram-negative pathogen found in hospitals and intensive care units.Whereas in Escherichia coli and Salmonella, increased production of the outer membrane acyltransferase PagP results in formation of protective hepta-acylated lipid A, which reinforces the lipopolysaccharide portion of the outer membrane barrier, A. baumannii does not carry a gene that encodes a PagP homolog.Emergence of multidrug- and extremely drug-resistant A. baumannii illustrates the ineffectiveness of current prevention and treatment options.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Biosciences, University of Texas at Austin, Austin, Texas, USA.

No MeSH data available.


Related in: MedlinePlus

Structural characterization of the A. baumannii secondary lipid A acyltransferases. Characterization of lipid A isolated from A. baumannii strains. (A) 32P-radiolabeled lipid A from A. baumannii was isolated and separated based on hydrophobicity using TLC. Fatty acyl chains bearing a hydroxyl group at position 3 are indicated in red. (B) MALDI-TOF MS and structures of wild-type A. baumannii lipid A with m/z ratios of 1,729.12 and 1,911.29, corresponding to the hexa- and hepta-acylated species, respectively. Addition of a hydroxyl group (red) corresponds to the m/z ratios 1,713.13 and 1,895.16. (C) MALDI-TOF MS of the ΔlpxLAb mutant indicating a major species at m/z 1,713.1. (D) MALDI-TOF MS of the ΔlpxMAb mutant indicating a major species at m/z 1,546.0. Addition of the hydroxyl group to lipid A (red) results in a lipid A at m/z 1,530.96.
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fig2: Structural characterization of the A. baumannii secondary lipid A acyltransferases. Characterization of lipid A isolated from A. baumannii strains. (A) 32P-radiolabeled lipid A from A. baumannii was isolated and separated based on hydrophobicity using TLC. Fatty acyl chains bearing a hydroxyl group at position 3 are indicated in red. (B) MALDI-TOF MS and structures of wild-type A. baumannii lipid A with m/z ratios of 1,729.12 and 1,911.29, corresponding to the hexa- and hepta-acylated species, respectively. Addition of a hydroxyl group (red) corresponds to the m/z ratios 1,713.13 and 1,895.16. (C) MALDI-TOF MS of the ΔlpxLAb mutant indicating a major species at m/z 1,713.1. (D) MALDI-TOF MS of the ΔlpxMAb mutant indicating a major species at m/z 1,546.0. Addition of the hydroxyl group to lipid A (red) results in a lipid A at m/z 1,530.96.

Mentions: To analyze the effect on lipid A produced by each A. baumannii strain, 32P-radiolabeled lipid A was isolated and chromatographically separated based on hydrophobicity. Quantitative thin-layer chromatography (TLC) showed that wild-type A. baumannii produced a predominant hepta-acylated lipid A species with relatively minor amounts of a hexa-acylated species (Fig. 2A, lane 1). Strains with deletions in the LpxLAb and LpxMAb genetic coding sequences exhibited reduced hydrophobic migration patterns indicative of decreased acylation relative to the wild-type strain (Fig. 2A, lanes 2 and 4). Complementation restored production of wild-type hepta-acylated lipid A in each mutant strain (Fig. 2A, lanes 3 and 5). Unlike the well-defined E. coli lipid A biosynthetic pathway, these initial results also indicate that secondary acylation in A. baumannii is not strictly ordered, since both lpxLAb and lpxMAb mutants retain secondary acyl chains.


Reinforcing Lipid A Acylation on the Cell Surface of Acinetobacter baumannii Promotes Cationic Antimicrobial Peptide Resistance and Desiccation Survival.

Boll JM, Tucker AT, Klein DR, Beltran AM, Brodbelt JS, Davies BW, Trent MS - MBio (2015)

Structural characterization of the A. baumannii secondary lipid A acyltransferases. Characterization of lipid A isolated from A. baumannii strains. (A) 32P-radiolabeled lipid A from A. baumannii was isolated and separated based on hydrophobicity using TLC. Fatty acyl chains bearing a hydroxyl group at position 3 are indicated in red. (B) MALDI-TOF MS and structures of wild-type A. baumannii lipid A with m/z ratios of 1,729.12 and 1,911.29, corresponding to the hexa- and hepta-acylated species, respectively. Addition of a hydroxyl group (red) corresponds to the m/z ratios 1,713.13 and 1,895.16. (C) MALDI-TOF MS of the ΔlpxLAb mutant indicating a major species at m/z 1,713.1. (D) MALDI-TOF MS of the ΔlpxMAb mutant indicating a major species at m/z 1,546.0. Addition of the hydroxyl group to lipid A (red) results in a lipid A at m/z 1,530.96.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4442142&req=5

fig2: Structural characterization of the A. baumannii secondary lipid A acyltransferases. Characterization of lipid A isolated from A. baumannii strains. (A) 32P-radiolabeled lipid A from A. baumannii was isolated and separated based on hydrophobicity using TLC. Fatty acyl chains bearing a hydroxyl group at position 3 are indicated in red. (B) MALDI-TOF MS and structures of wild-type A. baumannii lipid A with m/z ratios of 1,729.12 and 1,911.29, corresponding to the hexa- and hepta-acylated species, respectively. Addition of a hydroxyl group (red) corresponds to the m/z ratios 1,713.13 and 1,895.16. (C) MALDI-TOF MS of the ΔlpxLAb mutant indicating a major species at m/z 1,713.1. (D) MALDI-TOF MS of the ΔlpxMAb mutant indicating a major species at m/z 1,546.0. Addition of the hydroxyl group to lipid A (red) results in a lipid A at m/z 1,530.96.
Mentions: To analyze the effect on lipid A produced by each A. baumannii strain, 32P-radiolabeled lipid A was isolated and chromatographically separated based on hydrophobicity. Quantitative thin-layer chromatography (TLC) showed that wild-type A. baumannii produced a predominant hepta-acylated lipid A species with relatively minor amounts of a hexa-acylated species (Fig. 2A, lane 1). Strains with deletions in the LpxLAb and LpxMAb genetic coding sequences exhibited reduced hydrophobic migration patterns indicative of decreased acylation relative to the wild-type strain (Fig. 2A, lanes 2 and 4). Complementation restored production of wild-type hepta-acylated lipid A in each mutant strain (Fig. 2A, lanes 3 and 5). Unlike the well-defined E. coli lipid A biosynthetic pathway, these initial results also indicate that secondary acylation in A. baumannii is not strictly ordered, since both lpxLAb and lpxMAb mutants retain secondary acyl chains.

Bottom Line: Acinetobacter baumannii is an emerging Gram-negative pathogen found in hospitals and intensive care units.Whereas in Escherichia coli and Salmonella, increased production of the outer membrane acyltransferase PagP results in formation of protective hepta-acylated lipid A, which reinforces the lipopolysaccharide portion of the outer membrane barrier, A. baumannii does not carry a gene that encodes a PagP homolog.Emergence of multidrug- and extremely drug-resistant A. baumannii illustrates the ineffectiveness of current prevention and treatment options.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Biosciences, University of Texas at Austin, Austin, Texas, USA.

No MeSH data available.


Related in: MedlinePlus