Spatially distinct and metabolically active membrane domain in mycobacteria

Proc Natl Acad Sci U S A. 2016 May 10;113(19):5400-5. doi: 10.1073/pnas.1525165113. Epub 2016 Apr 25.


Protected from host immune attack and antibiotic penetration by their unique cell envelope, mycobacterial pathogens cause devastating human diseases such as tuberculosis. Seamless coordination of cell growth with cell envelope elongation at the pole maintains this barrier. Unraveling this spatiotemporal regulation is a potential strategy for controlling mycobacterial infections. Our biochemical analysis previously revealed two functionally distinct membrane fractions in Mycobacterium smegmatis cell lysates: plasma membrane tightly associated with the cell wall (PM-CW) and a distinct fraction of pure membrane free of cell wall components (PMf). To provide further insight into the functions of these membrane fractions, we took the approach of comparative proteomics and identified more than 300 proteins specifically associated with the PMf, including essential enzymes involved in cell envelope synthesis such as a mannosyltransferase, Ppm1, and a galactosyltransferase, GlfT2. Furthermore, comparative lipidomics revealed the distinct lipid composition of the PMf, with specific association of key cell envelope biosynthetic precursors. Live-imaging fluorescence microscopy visualized the PMf as patches of membrane spatially distinct from the PM-CW and notably enriched in the pole of the growing cells. Taken together, our study provides the basis for assigning the PMf as a spatiotemporally distinct and metabolically active membrane domain involved in cell envelope biogenesis.

Keywords: cell envelope; lipid biosynthesis; membrane domain; mycobacteria; polar growth.

Publication types

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

MeSH terms

  • Bacterial Proteins / metabolism*
  • Lipid Metabolism / physiology*
  • Membrane Microdomains / metabolism*
  • Membrane Microdomains / ultrastructure*
  • Membrane Proteins / metabolism*
  • Mycobacterium / metabolism*
  • Mycobacterium / ultrastructure*


  • Bacterial Proteins
  • Membrane Proteins