Identification of novel lipid modifications and intermembrane dynamics in Corynebacterium glutamicum using

Stephan Klatt1, Rajini Brammananth2, Sean O'Callaghan3

  • 1Department of Biochemistry and Molecular Biology University of Melbourne, Parkville, Victoria 3010, Australia.

Insights

This study reveals novel lipid compositions in Corynebacterineae cell envelopes, uncovering connections between lipid transport and synthesis in Corynebacterium glutamicum.

Area of Science:

  • Microbiology
  • Cell Biology
  • Biochemistry

Background:

  • The complex cell envelopes of Corynebacterineae, including pathogens like Mycobacterium tuberculosis and nonpathogens like Corynebacterium glutamicum, are crucial for their survival and virulence.
  • The cell envelope structure consists of an asymmetric outer membrane, an arabinogalactan-peptidoglycan complex, and an inner cell membrane.
  • Understanding the lipid composition of these membranes is key to elucidating cell envelope biogenesis.

Purpose of the Study:

  • To conduct the first high-resolution analysis of lipids in the inner and outer membranes of Corynebacterium glutamicum.
  • To identify and characterize the lipid subclasses and molecular species present in these membranes.
  • To investigate the impact of specific protein deletions on lipid distribution and synthesis.

Main Methods:

  • High-resolution liquid chromatography-tandem mass spectrometry (LC/MS/MS) was employed for lipid analysis.
  • Mass spectral library searches in MS-DIAL were used for lipid identification.
  • Differential solvent extraction was utilized to generate inner and outer membrane fractions.
  • Genetic manipulation, specifically the deletion of the TmaT protein, was performed.

Main Results:

  • A comprehensive lipid profile of C. glutamicum membranes was established, identifying 28 lipid (sub)classes and over 233 molecular species.
  • New subclasses of acylated/acetylated trehalose mono/dicorynomycolic acids were discovered.
  • All identified lipid subclasses showed polarized distribution between the inner and outer membrane fractions.
  • Deletion of TmaT resulted in triacylglycerol accumulation in the inner membrane and reduced synthesis of phosphatidylglycerol and alanylated lipids.

Conclusions:

  • This research provides the first detailed lipid map of Corynebacterium glutamicum inner and outer membranes.
  • The findings highlight a previously unrecognized link between the synthesis and/or transport of diverse lipid classes.
  • The study underscores the importance of TmaT in regulating lipid homeostasis within the cell envelope.

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