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Journal of Bacteriology, September 1999, p. 5341-5349, Vol. 181, No. 17
Philipps-Universität Marburg,
Biochemie-FB Chemie, D-35032 Marburg, Germany
Received 22 March 1999/Accepted 22 June 1999
Bacillus subtilis has developed sophisticated
mechanisms to withstand fluctuations in temperature. Membrane fatty
acids are the major determinants for a sufficiently fluid membrane
state to ensure the membrane's function at all temperatures. The fatty acid profile of B. subtilis is characterized by a high
content of branched fatty acids irrespective of the growth medium.
Here, we report on the importance of isoleucine for B. subtilis to survive cold shock from 37 to 15°C. Cold shock
experiments with strain JH642 revealed a cold-protective function for
all intermediates of anteiso-branched fatty acid biosynthesis.
Metabolites related to iso-branched or straight-chain fatty acid
biosynthesis were not protective. Fatty acid profiles of different
B. subtilis wild-type strains proved the altered branching
pattern by an increase in the anteiso-branched fatty acid content and a
concomitant decrease of iso-branched species during cold shock. There
were no significant changes in the fatty acid saturation or acyl chain
length. The cold-sensitive phenotype of isoleucine-deficient strains in
the absence of isoleucine correlated with their inability to synthesize more anteiso-branched fatty acids, as shown by the fatty acid profile.
The switch to a fatty acid profile dominated by
anteiso-C15:0 and C17:0 at low temperatures and
the cold-sensitive phenotype of isoleucine-deficient strains in the
absence of isoleucine focused our attention on the critical role of
anteiso-branched fatty acids in the growth of B. subtilis
in the cold.
0021-9193/99/$04.00+0
Copyright © 1999, American Society for Microbiology. All rights reserved.
Cold Shock Response of Bacillus
subtilis: Isoleucine-Dependent Switch in the Fatty Acid Branching
Pattern for Membrane Adaptation to Low Temperatures
*
Corresponding author. Mailing address:
Philipps-Universität Marburg, FB Chemie-Biochemie,
Hans-Meerwein-Strasse, D-35032 Marburg. Phone: 49 6421-285722. Fax: 49 6421-282191. E-mail: marahiel{at}chemie.uni-marburg.de.
This is dedicated to Rudolf K. Thauer for his 60th birthday.
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