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J. Bacteriol., Jun 1997, 3430-3436, Vol 179, No. 11
C Hoischen, K Gura, C Luge and J Gumpert
The cells of an L-form strain of Streptomyces hygroscopicus have been grown
for 20 years without a cell wall. Their cytoplasmic membranes have high
stability and an unusual structural polymorphism. To clarify the importance
of the lipid components for these membrane properties, a comparative
analysis has been carried out with purified membranes of L- form cells, of
parent vegetative hyphal cells (N-form cells), and of protoplasts derived
from the latter. The phospholipid classes and fatty acids were determined
by thin-layer chromatography (TLC), two- dimensional TLC, high-performance
liquid chromatography, gas chromatography, and mass spectrometry. The
qualitative compositions of cardiolipin (CL), lyso-cardiolipin (LCL),
phosphatidylethanolamine (PE1 and PE2), lyso-phosphatidylethanolamine
(LPE), phosphatidylinositolmannoside (PIM), phosphatidic acid (PA), dilyso-
cardiolipin-phosphatidylinositol (DLCL-PI), and the 13 main fatty acids
were the same in the three membrane types. However, significant
quantitative differences were observed in the L-form membrane. They consist
of a three- to fourfold-higher content of total, extractable lipids, 20%
more phospholipids, an increased content of CL and PIM, and a reduced
amount of the component DLCL-PI. Furthermore, the L-form membrane is
characterized by a higher content of branched anteiso 15:0 and anteiso 17:0
fatty acids compared to that of the membranes of the walled vegetative
cells. These fatty acids have lower melting points than their straight and
iso-branched counterparts and make the membrane more fluid. The
phospholipid composition of the protoplast membrane differs quantitatively
from that of the N form and the L form. Whereas the phospholipid classes
are mostly similar to that of the N form, the fatty acid pattern tends to
be closer to that of the L-form membrane. The membranes of both the L-form
cells and the protoplasts need to be more fluid because of their spherical
cell shape and higher degree of curvature compared with N-form membranes.
Copyright © 1997, American Society for Microbiology
Lipid and fatty acid composition of cytoplasmic membranes from Streptomyces hygroscopicus and its stable protoplast-type L form
Institut fur Molekulare Biotechnologie, Jena, Germany.
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