Structural and Functional Conversion of Molecular Chaperone ClpB from the Gram-Positive Halophilic Lactic Acid Bacterium Tetragenococcus halophilus Mediated by ATP and Stress
| Autor: | Shinya Sugimoto, Jiro Nakayama, Hiroyuki Yoshida, Kenji Sonomoto, Keigo Tsuruno, Yoshimitsu Mizunoe |
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| Rok vydání: | 2006 |
| Předmět: |
Hot Temperature
Dimer Molecular Sequence Data Size-exclusion chromatography Random hexamer medicine.disease_cause Microbiology Potassium Chloride Structure-Activity Relationship chemistry.chemical_compound Adenosine Triphosphate Bacterial Proteins Affinity chromatography Tetragenococcus halophilus Escherichia coli medicine Molecular Biology Heat-Shock Proteins Chromatography biology biology.organism_classification Enzymes and Proteins Recombinant Proteins Lactobacillus Biochemistry chemistry Chaperone (protein) biology.protein CLPB Dimerization |
| Zdroj: | Journal of Bacteriology. 188:8070-8078 |
| ISSN: | 1098-5530 0021-9193 |
| DOI: | 10.1128/jb.00404-06 |
| Popis: | In this study, we report the purification, initial structural characterization, and functional analysis of the molecular chaperone ClpB from the gram-positive, halophilic lactic acid bacterium Tetragenococcus halophilus . A recombinant T. halophilus ClpB (ClpB Tha ) was overexpressed in Escherichia coli and purified by affinity chromatography, hydroxyapatite chromatography, and gel filtration chromatography. As demonstrated by gel filtration chromatography, chemical cross-linking with glutaraldehyde, and electron microscopy, ClpB Tha forms a homohexameric single-ring structure in the presence of ATP under nonstress conditions. However, under stress conditions, such as high-temperature (>45°C) and high-salt concentrations (>1 M KCl), it dissociated into dimers and monomers, regardless of the presence of ATP. The hexameric ClpB Tha reactivated heat-aggregated proteins dependent upon the DnaK system from T. halophilus (KJE Tha ) and ATP. Interestingly, the mixture of dimer and monomer ClpB Tha , which was formed under stress conditions, protected substrate proteins from thermal inactivation and aggregation in a manner similar to those of general molecular chaperones. From these results, we hypothesize that ClpB Tha forms dimers and monomers to function as a holding chaperone under stress conditions, whereas it forms a hexamer ring to function as a disaggregating chaperone in cooperation with KJE Tha and ATP under poststress conditions. |
| Databáze: | OpenAIRE |
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