Kälteschockadaptation von Bacillus subtilis: Identifizierung kälteinduzierter Gene und Proteine und Untersuchung ihrer kältespezifischen Funktion und Regulation
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Philipps-Universität Marburg
Abstract
Unknown cold-induced proteins and genes of
Bacillus subtilis were identified by two-dimensional
gelelectrophoresis and genomewide transcriptional analysis. The
role of the cold-induced genes in the adaptation to low
temperature was investigated. A cold-specific phenotype was
observed for a yplP deletion mutant and a yqfR/ydbR
double-deletion mutant. The yplP-gene encodes a sigL-dependent
transcriptional activators in B. subtilis. The YplP-regulon is
currently unknown. The genes yqfR and YdbR encode for DEAD-box
mRNA-helicases, which were already identified as cold-induced
proteins in several microorganisms. It could be demonstrated by
fluorescence-microscopy of helicase-gfp fusions that the RNA
helicase co-localize at the cell-poles with coldshock-proteins
and ribosomes, depending on active transcription. Based on this
experiment the following model was proposed: The RNA-helicases
unwind cold-stabilized secondary structures of mRNA. After that
the coldshock-proteins bind to the mRNA to prevent refolding of
mRNA, resulting in efficient initiation of translation at low
temperatures. In addition the regulation of the fatty-acid
desaturase Des of Bacillus subtilis was investigated. The
desaturase Des maintains the fluidity of the membrane after
coldshock by synthesis of unsaturated fatty-acids in the
membrane. Genetic studies could show that the transcription of
the des-gene is regulated by the temperature-sensitive
two-component system DesKR of Bacillus subtilis. The
cold-specific regulation of other genes by DesKR could be
excluded.
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This item has been published with the following license: In Copyright