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Updated: Aug 20, 2026

Identification of Inositol Phosphate or Phosphoinositide Interacting Proteins by Affinity Chromatography Coupled to Western Blot or Mass Spectrometry
08:07

Identification of Inositol Phosphate or Phosphoinositide Interacting Proteins by Affinity Chromatography Coupled to Western Blot or Mass Spectrometry

Published on: July 26, 2019

Function of phosphatidylinositol in mycobacteria

Ruth E Haites1, Yasu S Morita, Malcolm J McConville

  • 1Department of Microbiology and Immunology, University of Melbourne, Parkville, Victoria 3010, Australia.

The Journal of Biological Chemistry
|January 7, 2005
PubMed

Insights

Large pools of phosphatidylinositol (PI) and PI mannosides (PIMs) are not essential for mycobacterial membrane integrity. However, these lipids are crucial for sustaining polar PIM biosynthesis, vital for mycobacterial growth.

Area of Science:

  • Microbiology
  • Molecular Biology
  • Biochemistry

Background:

  • Phosphatidylinositol (PI) is a key phospholipid in mycobacteria, serving as a precursor for complex glycolipids like PI mannosides (PIMs) and lipoarabinomannan (LAM).
  • The functional requirement of large steady-state pools of PI and apolar PIMs for mycobacterial growth remains unclear.

Purpose of the Study:

  • To investigate the necessity of large phosphatidylinositol (PI) and apolar PI mannoside (PIM) pools for mycobacterial growth.
  • To elucidate the role of these lipids in mycobacterial cell wall biosynthesis and viability.

Main Methods:

  • Generation of a Mycobacterium smegmatis inositol auxotroph by disrupting the ino1 gene.
  • Culturing the mutant under varying inositol concentrations and assessing growth rates, lipid levels, and viability.
  • Utilizing metabolic labeling to trace lipid turnover and biosynthesis pathways.

Main Results:

  • The ino1 mutant exhibited wild-type growth and lipid profiles in the presence of inositol.
  • Inositol starvation led to rapid depletion of PI and apolar PIMs without affecting viability.
  • Depletion of polar PIMs, however, coincided with cell wall component loss and reduced viability.
  • Metabolic labeling confirmed PI and apolar PIMs sustain polar PIM and LAM biosynthesis during nutrient limitation.

Conclusions:

  • Large pools of PI and apolar PIMs are not essential for maintaining mycobacterial membrane integrity.
  • These lipid pools are critical for supporting the biosynthesis of polar PIMs, a process essential for mycobacterial growth.
  • PI catabolism occurs via lyso-PI under non-limiting conditions.

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