Differences in membrane fluidity and fatty acid composition between phenotypic variants of Streptococcus pneumoniae

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Monitoring Changes in Membrane Polarity, Membrane Integrity, and Intracellular Ion Concentrations in Streptococcus pneumoniae Using Fluorescent Dyes
11:17

Monitoring Changes in Membrane Polarity, Membrane Integrity, and Intracellular Ion Concentrations in Streptococcus pneumoniae Using Fluorescent Dyes

Published on: February 17, 2014

Barak Aricha1, Itzhak Fishov, Zvi Cohen

  • 1Pediatric Infectious Disease Unit, Soroka University Medical Center, P.O. Box 151, Beer Sheva 84101, Israel. npurat@bgumail.bgu.ac.il

Journal of Bacteriology
|July 3, 2004
PubMed

Insights

Phase variation in Streptococcus pneumoniae affects bacterial membrane characteristics. Opaque variants exhibit reduced membrane fluidity due to altered fatty acid composition, impacting pneumococcal disease pathogenesis.

Area of Science:

  • Microbiology
  • Biochemistry
  • Pathogenesis

Background:

  • Phase variation in Streptococcus pneumoniae influences colonial opacity and is linked to disease.
  • Understanding membrane properties is crucial for deciphering pneumococcal pathogenesis.

Purpose of the Study:

  • To investigate the correlation between membrane characteristics and colony morphology in Streptococcus pneumoniae.
  • To determine how phase variation affects bacterial membrane fluidity and composition.

Main Methods:

  • Assessed membrane fluidity using pyrene excimerization and 1,6-diphenyl 1,3,5-hexatriene (DPH) fluorescence polarization.
  • Analyzed membrane fatty acid composition via gas chromatography.
  • Compared opaque and transparent variants of S. pneumoniae strains with different capsular types.

Main Results:

  • Opaque variants showed significantly decreased membrane fluidity (16-26% lower pyrene excimerization rate) compared to transparent variants.
  • Liposomes from opaque variants exhibited even greater reductions in fluidity (27-38%).
  • DPH fluorescence anisotropy indicated increased microviscosity in opaque variants (9-21% higher).
  • Fatty acid analysis revealed differences in proportions, with opaque variants having fewer unsaturated fatty acids.

Conclusions:

  • A distinct correlation exists between phase variation and altered membrane fluidity in Streptococcus pneumoniae.
  • Changes in membrane fluidity are likely due to variations in fatty acid composition between opaque and transparent phenotypes.
  • These findings contribute to understanding the role of membrane properties in pneumococcal pathogenesis.

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