Peptidoglycan-associated lipoprotein (Pal) of Gram-negative bacteria: function, structure, role in pathogenesis and potential application in immunoprophylaxis

FEMS Microbiol Lett. 2009 Sep;298(1):1-11. doi: 10.1111/j.1574-6968.2009.01659.x. Epub 2009 May 21.


The protein Pal (peptidoglycan-associated lipoprotein) is anchored in the outer membrane (OM) of Gram-negative bacteria and interacts with Tol proteins. Tol-Pal proteins form two complexes: the first is composed of three inner membrane Tol proteins (TolA, TolQ and TolR); the second consists of the TolB and Pal proteins linked to the cell's OM. These complexes interact with one another forming a multiprotein membrane-spanning system. It has recently been demonstrated that Pal is essential for bacterial survival and pathogenesis, although its role in virulence has not been clearly defined. This review summarizes the available data concerning the structure and function of Pal and its role in pathogenesis.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Bacterial Outer Membrane Proteins / chemistry
  • Bacterial Outer Membrane Proteins / immunology*
  • Bacterial Outer Membrane Proteins / physiology*
  • Gram-Negative Bacteria / chemistry
  • Gram-Negative Bacteria / immunology*
  • Gram-Negative Bacteria / pathogenicity*
  • Lipoproteins / chemistry
  • Lipoproteins / immunology*
  • Lipoproteins / physiology*
  • Models, Biological
  • Models, Molecular
  • Virulence
  • Virulence Factors / chemistry
  • Virulence Factors / immunology
  • Virulence Factors / physiology


  • Bacterial Outer Membrane Proteins
  • Lipoproteins
  • Virulence Factors