Open AccessMolecular evolution of biomembranes: structural equivalents and phylogenetic precursors of sterols.
Author(s) -
Michel Rohmer,
Pierrette Bouvier,
Guy Ourisson
Publication year - 1979
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.76.2.847
Subject(s) - membrane , hopanoids , triterpene , biochemistry , chemistry , amphiphile , biology , biosynthesis , function (biology) , stereochemistry , biophysics , enzyme , microbiology and biotechnology , organic chemistry , medicine , paleontology , alternative medicine , pathology , structural basin , copolymer , source rock , polymer
Derivatives of one triterpene family, the hopane family, are widely distributed in prokaryotes; they may be localized in membranes, playing there the same role as sterols play in eukaryotes, as a result of their similar size, rigidity, and amphiphilic character. Their biosynthesis embodies many primitive features compared to that of sterols and could have evolved toward the latter once aerobic conditions had been established. Membrane reinforcement appears to be achieved in other prokaryotes by other mechanisms, involving either approximately 40-A-long rigid hydrocarbon chains terminated by one polar group acting like a peg through the double-layer or similar chains terminated by two polar groups acting like tie-bars across the membrane. These inserts can be tetraterpenes (e.g., carotenoids). The biophysical function of membrane optimizers appears to have evolved toward sterols by changes limited to only a few enzymatic steps of the same fundamental biosynthetic processes.