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Updated: Jul 14, 2026

PIP-on-a-chip: A Label-free Study of Protein-phosphoinositide Interactions
10:58

PIP-on-a-chip: A Label-free Study of Protein-phosphoinositide Interactions

Published on: July 27, 2017

Molecular recognition and interfacial catalysis by the essential phosphatidylinositol mannosyltransferase PimA from

Marcelo E Guerin1, Jana Kordulakova, Francis Schaeffer

  • 1Unité de Biochimie Structurale (CNRS URA 2185), Institut Pasteur, 25 rue du Docteur Roux, 75724 Paris Cedex 15, France.

The Journal of Biological Chemistry
|May 19, 2007
PubMed

Insights

Mycobacterial phosphatidylinositol mannosides (PIMs) are crucial for host-pathogen interactions. Researchers elucidated the novel membrane-binding mechanism of Mycobacterium smegmatis PimA, revealing its role in initiating PIM biosynthesis and offering targets for antimycobacterial drug development.

Area of Science:

  • Biochemistry
  • Microbiology
  • Structural Biology

Background:

  • Mycobacterial cell wall components, including phosphatidylinositol mannosides (PIMs), are vital for host-pathogen interactions.
  • The biosynthetic pathways for PIMs and related lipoglycans in mycobacteria remain largely uncharacterized.
  • PimA is an essential enzyme in Mycobacterium smegmatis, catalyzing the initial mannosylation of phosphatidylinositol.

Purpose of the Study:

  • To elucidate the structure and function of Mycobacterium smegmatis PimA.
  • To understand the mechanism of phosphatidylinositol recognition and catalysis by PimA.
  • To explore the role of interfacial catalysis in early PIM biosynthesis.

Main Methods:

  • X-ray crystallography to determine the structure of PimA in complex with GDP-mannose.
  • Calorimetry and mutagenesis studies to investigate enzyme-membrane interactions.
  • Enzyme activity assays with varying substrate and surfactant concentrations.

Main Results:

  • The crystal structure revealed a two-domain GT-B glycosyltransferase organization for PimA.
  • PimA exhibits amphitrophic behavior, binding phosphatidylinositol and showing enhanced activity with anionic surfactants.
  • A model was proposed where PimA's N-terminal domain mediates membrane attachment and enzyme activation.
  • A novel mode of phosphatidylinositol recognition involving lipid-water interfacial catalysis was identified.

Conclusions:

  • PimA utilizes a unique mechanism involving membrane association for activation and catalysis in PIM biosynthesis.
  • Understanding PimA's function provides insights into mycobacterial cell wall synthesis.
  • The findings offer a structural basis for designing novel antimycobacterial agents targeting PIM synthesis.

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