Mycobacterium tuberculosis LppM Displays an Original Structure and Domain Composition Linked to a Dual Localization

Structure. 2016 Oct 4;24(10):1788-1794. doi: 10.1016/j.str.2016.07.009. Epub 2016 Aug 25.


Mycobacterium tuberculosis (Mtb) encodes several bacterial effectors impacting the colonization of phagocytes. LppM (Rv2171) is both implicated in phagocytosis and able to efficiently block phagosomal acidification in the macrophage, two key processes contributing to Mtb persistence. We show that LppM is anchored to the mycobacterial cell wall by a C-terminal membrane domain. However, the protein also exists as a truncated protein secreted into the culture medium. The LppM solution structure we solve here displays no similarity with other Mtb lipoproteins also involved in phagosomal maturation (i.e., LprG). In addition, we demonstrate that the protein may be able to bind rare molecular species of phosphatidylinositol mannosides, bacterial compounds known to affect the host immune response. Thus, our data demonstrate a dual localization of LppM and provide a unique perspective on the regulation of protein secretion and localization in Mtb.

MeSH terms

  • Bacterial Proteins / chemistry
  • Bacterial Proteins / metabolism
  • Binding Sites
  • Cell Wall / metabolism*
  • Culture Media / chemistry
  • Gene Expression Regulation, Bacterial
  • Lipoproteins / chemistry*
  • Lipoproteins / metabolism*
  • Mass Spectrometry
  • Models, Molecular
  • Mycobacterium tuberculosis / chemistry
  • Mycobacterium tuberculosis / metabolism*
  • Phagocytosis
  • Phosphatidylinositols / metabolism*
  • Protein Domains
  • Protein Isoforms / chemistry
  • Protein Isoforms / metabolism
  • Protein Structure, Secondary


  • Bacterial Proteins
  • Culture Media
  • Lipoproteins
  • Phosphatidylinositols
  • Protein Isoforms
  • phosphatidylinositol mannoside