Structure and composition of intracytoplasmic membranes of Ectothiorhodospira mobilis

Saundra Herndon Oyewole, Stanley C. Holt

Research output: Contribution to journalArticle

2 Scopus citations

Abstract

The lamellar membrane stacks of Ectothiorhodospira mobilis were isolated and purified by a combination of lysozyme and osmotic shock treatment, followed by differential and density gradient centrifugation. Preparations of lamellar membranes were enriched at least 2.4-fold in the ratio of bacteriochlorophyll a to protein. Thin-sectioning, negative staining, platinumcarbon shadowing and freeze-etching were used to study the architecture of the membrane units. Both platinum-carbon shadowing and freeze-etching showed the outer surfaces of the isolated lamellar membrane stacks to be relatively smooth. Particles averaging 7 nm in diameter were seen on several faces following freeze-ctching. Non-polar amino acids amounted to 60% of the total amino acid composition. Lipids constituted 32% of the membrane dry weight. Phosphatidyl ethanolamine and diphosphatidyl glycerol were the major phospholipids. Fatty acids of 10-15 carbons represented a small fraction of both membrane and whole cell fatty acids. Monoenes constituted 36% of the total membrane fatty acids and 38.4% of the total whole cell fatty acids. The major fatty acids of both whole cells and purified membranes were C16:0, C18:1 and cyclopropane C19:0.

Original languageEnglish (US)
Pages (from-to)167-182
Number of pages16
JournalArchives of Microbiology
Volume107
Issue number2
DOIs
StatePublished - Mar 1 1976
Externally publishedYes

Keywords

  • Composition of membranes
  • Ectothiorhodospira mobilis
  • Electron microscopy
  • Isolation of membranes
  • Photosynthetic membranes
  • Structure of membranes

ASJC Scopus subject areas

  • Microbiology
  • Biochemistry
  • Molecular Biology
  • Genetics

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