Document Detail

GroES/GroEL and DnaK/DnaJ have distinct roles in stress responses and during cell cycle progression in Caulobacter crescentus.
MedLine Citation:
PMID:  16980445     Owner:  NLM     Status:  MEDLINE    
Misfolding and aggregation of protein molecules are major threats to all living organisms. Therefore, cells have evolved quality control systems for proteins consisting of molecular chaperones and proteases, which prevent protein aggregation by either refolding or degrading misfolded proteins. DnaK/DnaJ and GroES/GroEL are the best-characterized molecular chaperone systems in bacteria. In Caulobacter crescentus these chaperone machines are the products of essential genes, which are both induced by heat shock and cell cycle regulated. In this work, we characterized the viabilities of conditional dnaKJ and groESL mutants under different types of environmental stress, as well as under normal physiological conditions. We observed that C. crescentus cells with GroES/EL depleted are quite resistant to heat shock, ethanol, and freezing but are sensitive to oxidative, saline, and osmotic stresses. In contrast, cells with DnaK/J depleted are not affected by the presence of high concentrations of hydrogen peroxide, NaCl, and sucrose but have a lower survival rate after heat shock, exposure to ethanol, and freezing and are unable to acquire thermotolerance. Cells lacking these chaperones also have morphological defects under normal growth conditions. The absence of GroE proteins results in long, pinched filamentous cells with several Z-rings, whereas cells lacking DnaK/J are only somewhat more elongated than normal predivisional cells, and most of them do not have Z-rings. These findings indicate that there is cell division arrest, which occurs at different stages depending on the chaperone machine affected. Thus, the two chaperone systems have distinct roles in stress responses and during cell cycle progression in C. crescentus.
Michelle F Susin; Regina L Baldini; Frederico Gueiros-Filho; Suely L Gomes
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2006-09-15
Journal Detail:
Title:  Journal of bacteriology     Volume:  188     ISSN:  0021-9193     ISO Abbreviation:  J. Bacteriol.     Publication Date:  2006 Dec 
Date Detail:
Created Date:  2006-11-19     Completed Date:  2006-12-27     Revised Date:  2009-11-18    
Medline Journal Info:
Nlm Unique ID:  2985120R     Medline TA:  J Bacteriol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  8044-53     Citation Subset:  IM    
Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, Av. Prof. Lineu Prestes 748, 05508-000, São Paulo, SP, Brasil.
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MeSH Terms
Adenosine Triphosphatases / genetics,  physiology*
Bacterial Proteins / genetics,  physiology*
Cell Division
Heat-Shock Proteins / genetics,  physiology*
Molecular Chaperones / genetics,  physiology*
Osmotic Pressure
Oxidative Stress
Proteobacteria / cytology,  growth & development,  physiology*
Sodium Chloride
Reg. No./Substance:
0/Bacterial Proteins; 0/Heat-Shock Proteins; 0/Molecular Chaperones; 64-17-5/Ethanol; 7647-14-5/Sodium Chloride; EC 3.6.1.-/Adenosine Triphosphatases; EC 3.6.1.-/DnaK protein, Brevibacillus choshinensis

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