On the oligomeric state of chloroplast chaperonin 10 and chaperonin 20
| Autor: | Celeste Weiss, Itzhak Mizrahi, Paul V. Viitanen, Abdussalam Azem, Ariel Lustig, Anat L. Bonshtien, Rajach Sharkia, Adina Niv |
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| Rok vydání: | 2003 |
| Předmět: |
Protein Folding
Chloroplasts Chaperonins Macromolecular Substances Polymers Swine Protein subunit Biophysics Arabidopsis macromolecular substances Biology Biochemistry Oligomer Analytical Chemistry Chaperonin chemistry.chemical_compound Malate Dehydrogenase Group I Chaperonins Chaperonin 10 Animals Molecular Biology Arabidopsis Proteins GroES Chaperonin 60 GroEL Chloroplast enzymes and coenzymes (carbohydrates) Protein Subunits Cross-Linking Reagents chemistry biological sciences bacteria Protein folding |
| Zdroj: | Biochimica et biophysica acta. 1651(1-2) |
| ISSN: | 0006-3002 |
| Popis: | Type I chaperonins are fundamental protein folding machineries that function in eubacteria, mitochondria and chloroplasts. Eubacteria and mitochondria contain chaperonin systems comprised of homo-oligomeric chaperonin 60 tetradecamers and co-chaperonin 10 heptamers. In contrast, the chloroplast chaperonins are heterooligomeric tetradecamers that are composed of two subunit types, alpha and beta. Additionally, chloroplasts contain two structurally distinct co-chaperonins. One, ch-cpn10, is probably similar to the mitochondrial and bacterial co-chaperonins, and is composed of 10 kDa subunits. The other, termed ch-cpn20 is composed of two cpn10-like domains that are held together by a short linker. While the oligomeric structure of ch-cpn10 remains to be elucidated, it was previously suggested that ch-cpn20 forms tetramers in solution, and that this is the functional oligomer. In the present study, we investigated the properties of purified ch-cpn10 and ch-cpn20. Using bifunctional cross-linking reagents, gel filtration chromatography and analytical ultracentrifugation, we show that ch-cpn10 is a heptamer in solution. In contrast, ch-cpn20 forms multiple oligomers that are in dynamic equilibrium with each other and cover a broad spectrum of molecular weights in a concentration-dependent manner. However, upon association with GroEL, only one type of co-chaperonin-GroEL complex is formed. |
| Databáze: | OpenAIRE |
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