AIMS: To find out membrane tolerance strategy to ethanol in Bacillus subtilis that possesses a powerful system of protection against environmental stresses. METHODS AND RESULTS: Cytoplasmic membranes of B. subtilis were severely affected by even short-term exposure to 3% (v/v) ethanol: the growth rate and membrane protein synthesis were markedly reduced, and no adaptive alterations in phospholipids were detected. Simultaneously, steady-state DPH fluorescence anisotropy (r(ss)) showed that the membrane rigidity increased substantially. Analysis of the membrane phosphoproteome using in vitro labelling with [γ-(32) P]ATP revealed the association of DnaK and GroEL chaperones with membrane, indicating a stress induction process. Upon a long-term 3% (v/v) ethanol stress, the cell growth accelerated slightly and the composition of polar head groups and fatty acids of membrane phospholipids underwent an extensive reconstruction. Correspondingly, membrane fluidity turned back to the original r(ss) values of the control cells. CONCLUSIONS: In B. subtilis, the adaptive response to short-term ethanol stress comprises the recruitment of molecular chaperones on the impaired membrane structure; consequently, the phospholipid synthesis is restored and membrane fluidity adapts properly to the continuing ethanol stress. SIGNIFICANCE AND IMPACT OF THE STUDY: These findings underline the role of membrane lipids in establishing tolerance towards ethanol and also suggest the contribution of molecular chaperones to the membrane and cell recovery.
- MeSH
- Bacillus subtilis účinky léků růst a vývoj fyziologie MeSH
- bakteriální proteiny metabolismus MeSH
- buněčná membrána chemie metabolismus MeSH
- ethanol metabolismus farmakologie MeSH
- fluidita membrány účinky léků MeSH
- fluorescenční polarizace MeSH
- fosfolipidy metabolismus MeSH
- fyziologický stres MeSH
- mastné kyseliny analýza MeSH
- membránové lipidy chemie metabolismus MeSH
- molekulární chaperony metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- bakteriální proteiny MeSH
- ethanol MeSH
- fosfolipidy MeSH
- mastné kyseliny MeSH
- membránové lipidy MeSH
- molekulární chaperony MeSH
Processes occurring in the cytoplasmic membrane of the surfactin producer Bacillus subtilis were examined during a 3-d cultivation. The fatty acid composition was found to be almost stable within this interval, except for the early stationary phase when the nonbranched, mostly C(16:0) and C(18:0) (high melting fatty acids), prevailed transiently in the membrane. As for phospholipids, phosphatidylglycerol and phosphatidylethanolamine, representing 73 % of the total in the membranes of exponential cells were partly replaced by cardiolipin, which gradually rose from 5 to 28 % at the end of cultivation. In parallel, steady-state fluorescence anisotropy (r (s)) measurements with 1,6-diphenyl-1,3,5-hexatriene (DPH) indicated a remarkable increase of r (s) DPH during the long-term cultivation and implied a continuous rigidization of the membrane interior. By contrast, the almost constant values of r (s) 1-(4-trimethylammoniumphenyl)-6-phenyl-1,3,5-hexatriene 4-toluenesulfonate (TMA-DPH) reflected stable microviscosity of the membrane surface region. Thus, the significant increase of high melting fatty acids and cardiolipin in the cytoplasmic membrane together with the progressive rigidization of the membrane interior reflected the cell adaptation to adverse conditions.
- MeSH
- Bacillus subtilis chemie růst a vývoj metabolismus MeSH
- buněčná membrána chemie metabolismus MeSH
- cyklické peptidy chemie metabolismus MeSH
- fluorescenční polarizace MeSH
- kinetika MeSH
- lipopeptidy chemie metabolismus MeSH
- membránové lipidy chemie metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- cyklické peptidy MeSH
- lipopeptidy MeSH
- membránové lipidy MeSH
- surfactin peptide MeSH Prohlížeč
