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05:31
Purification and Visualization of Lipopolysaccharide from Gram-negative Bacteria by Hot Aqueous-phenol Extraction
Published on: May 28, 2012
Lipopolysaccharides mediate leukotoxin secretion in Aggregatibacter actinomycetemcomitans
G Tang1, T Kawai, H Komatsuzawa
1Department of Microbiology and Molecular Genetics, University of Vermont, Burlington, VT 05405, USA.
Molecular Oral Microbiology
|March 8, 2012
Summary
Lipopolysaccharide O-antigen affects leukotoxin secretion in Aggregatibacter actinomycetemcomitans. Altered O-antigen in an rmlC mutant reduced secreted leukotoxin and increased membrane-bound toxin, suggesting O-antigen
Area of Science:
- Microbiology
- Bacterial Pathogenesis
- Molecular Biology
Background:
- Aggregatibacter actinomycetemcomitans is a human pathogen.
- Lipopolysaccharide (LPS) O-antigen (O-PS) is a key component of the bacterial outer membrane.
- LPS glycosylation impacts bacterial virulence and interactions.
Purpose of the Study:
- To investigate the role of LPS O-antigen in the secretion of Aggregatibacter actinomycetemcomitans virulence factors.
- To determine the effect of altered O-PS on leukotoxin secretion mediated by the TolC-dependent type I secretion system.
Main Methods:
- Generated a mutant strain with inactivated TDP-4-keto-6-deoxy-d-glucose 3,5-epimerase (rmlC), leading to altered O-PS.
- Assessed the secretion of epithelial adhesin Aae, immunoglobulin Fc receptor Omp34, and leukotoxin in wild-type and mutant strains.
- Analyzed leukotoxin mRNA levels and vancomycin resistance.
- Complemented the rmlC gene in trans and overexpressed TolC.
Main Results:
- Leukotoxin secretion was significantly reduced (nine-fold) in the rmlC mutant, with a concurrent increase in membrane-bound toxin (four-fold).
- Secretion of Aae and Omp34 remained unaffected.
- The rmlC mutation affected TolC function, as evidenced by increased vancomycin resistance.
- Leukotoxin secretion was post-transcriptionally regulated in the O-PS modified strain.
Conclusions:
- O-antigen polysaccharides of LPS play a crucial role in mediating leukotoxin secretion in Aggregatibacter actinomycetemcomitans.
- The TolC-dependent type I secretion system's function is influenced by O-PS structure.
- O-PS modification impacts bacterial virulence factor secretion and antibiotic resistance.
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