Protein catabolism in growing Bacillus megaterium during adaptation to salt stress

Elevated concentration of NaCl in liquid medium caused a concentration-dependent growth delay (adaptation lag) and decrease in the maximal growth rate of Bacillus megaterium. The adaptation to salt stress was accompanied by transformation of some otherwise stable (long-lived; LLP) cell proteins into...

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Bibliographic Details
Published in:FEMS microbiology letters 2000-03, Vol.184 (2), p.173-177
Main Authors: Nekolny, David, Chaloupka, Jiřı́
Format: Article
Language:English
Subjects:
Bacillus megaterium
Growth adaptation
NaCl stress/shock
Osmotic stress/shock
Protein turnover
Proteolytic activity
Salt stress/shock
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Summary:Elevated concentration of NaCl in liquid medium caused a concentration-dependent growth delay (adaptation lag) and decrease in the maximal growth rate of Bacillus megaterium. The adaptation to salt stress was accompanied by transformation of some otherwise stable (long-lived; LLP) cell proteins into quickly degraded (short-lived; SLP) ones. Exposure to the strongly growth-reducing 1 M NaCl increased the size of the SLP ‘pool’ of intracellular proteins from about 5 to about 15% of total protein. The major intracellular proteolytic capacity of B. megaterium is represented by intracellular serine proteinases (ISP). Paradoxically, their specific activity was lowered or masked during the adaptation phase marked by increased catabolism of short-lived and/or destabilized proteins by the stress. This documents that intracellular proteolytic activity cannot be a key regulator of protein catabolism during adaptation to stress.
ISSN:0378-1097
1574-6968
DOI:10.1016/S0378-1097(00)00039-2