Dual orientation of the outer membrane lipoprotein Pal in Escherichia coli

Microbiology (Reading). 2015 Jun;161(6):1251-9. doi: 10.1099/mic.0.000084. Epub 2015 Mar 25.

Abstract

Peptidoglycan associated lipoprotein (Pal) of Escherichia coli (E. coli) is a characteristic bacterial lipoprotein, with an N-terminal lipid moiety anchoring it to the outer membrane. Since its discovery over three decades ago, Pal has been well studied for its participation in the Tol-Pal complex which spans the periplasm and has been proposed to play important roles in bacterial survival, pathogenesis and virulence. Previous studies of Pal place the lipoprotein in the periplasm of E. coli, allowing it to interact with Tol proteins and the peptidoglycan layer. Here, we describe for the first time, a subpopulation of Pal which is present on the cell surface of E. coli. Flow cytometry and confocal microscopy detect anti-Pal antibodies on the surface of intact E. coli cells. Interestingly, Pal is surface exposed in an 'all or nothing' manner, such that most of the cells contain only internal Pal, with fewer cells ( < 20 %) exhibiting surface Pal.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Bacterial Outer Membrane Proteins / analysis*
  • Escherichia coli / chemistry*
  • Escherichia coli Proteins / analysis*
  • Flow Cytometry
  • Lipoproteins / analysis*
  • Membrane Proteins / analysis*
  • Microscopy, Confocal
  • Peptidoglycan / analysis*

Substances

  • Bacterial Outer Membrane Proteins
  • Escherichia coli Proteins
  • ExcC protein, E coli
  • Lipoproteins
  • Membrane Proteins
  • Peptidoglycan