Outer membrane protein A, peptidoglycan-associated lipoprotein, and murein lipoprotein are released by Escherichia

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J Hellman1, P M Loiselle, M M Tehan

  • 1Department of Infectious Diseases, Massachusetts General Hospital and Harvard Medical School, Boston, Massachusetts, USA. hellman@etherdome.mgh.harvard.edu

Infection and Immunity
|April 18, 2000
PubMed

Insights

Gram-negative bacteria release outer membrane proteins (OMPs) during sepsis. This study identifies these OMPs as outer membrane protein A (OmpA), peptidoglycan-associated lipoprotein (PAL), and murein lipoprotein (MLP).

Area of Science:

  • Microbiology and Immunology
  • Bacterial Outer Membrane Proteins
  • Sepsis Pathogenesis

Background:

  • Gram-negative bacteria release outer membrane protein (OMP) and lipopolysaccharide (LPS) complexes during sepsis.
  • These OMPs are targeted by immunoglobulin G (IgG) in protective antisera, suggesting a role in immune response.
  • Identifying these specific OMPs is crucial for understanding sepsis mechanisms and developing therapeutic strategies.

Purpose of the Study:

  • To identify the three specific outer membrane proteins (OMPs) released by gram-negative bacteria in the presence of human serum and during experimental sepsis.
  • To characterize the molecular identity of OMPs recognized by cross-protective antibodies.

Main Methods:

  • Immunoblotting techniques were employed to identify the OMPs.
  • Studies utilized OmpA-deficient and PAL-deficient bacteria, alongside purified recombinant OmpA and peptide sequencing of purified proteins.
  • Murein lipoprotein (MLP)-deficient bacteria were also used for identification.

Main Results:

  • The 35-kDa OMP was identified as outer membrane protein A (OmpA).
  • The 18-kDa OMP was identified as peptidoglycan-associated lipoprotein (PAL).
  • The 5- to 9-kDa OMP was identified as murein lipoprotein (MLP).

Conclusions:

  • The study successfully identified the three major OMPs released by gram-negative bacteria in human serum and circulation during experimental sepsis.
  • These identified OMPs are OmpA, PAL, and MLP, providing critical targets for further immunological investigation and potential therapeutic development in sepsis.

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