Nucleotides and substrates trigger the dynamics of the Toc34 GTPase homodimer involved in chloroplast preprotein translocation
| Autor: | Björn Hellenkamp, Maik S. Sommer, Wolfgang Kügel, Thomas F. Prisner, Christina Lumme, Jan P. Medelnik, Jens Michaelis, Denise Schuetz, Thorsten Hugel, Manuela Dehmer, Jens Kretschmer, Enrico Schleiff, Hasret Altan-Martin, Mislav Oreb, Sevdalina Lyubenova, Reza Dastvan, Oliver Mirus |
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| Rok vydání: | 2013 |
| Předmět: |
Models
Molecular Chloroplasts Dimer Molecular Sequence Data Gene Expression GTPase Guanosine Diphosphate Substrate Specificity chemistry.chemical_compound GTP-binding protein regulators Structural Biology Escherichia coli Translocase Nucleotide Amino Acid Sequence Protein Precursors Molecular Biology Plant Proteins Molecular switch chemistry.chemical_classification biology Peas Membrane Proteins Recombinant Proteins Cell biology Chloroplast Kinetics Protein Transport Förster resonance energy transfer chemistry biology.protein Thermodynamics Guanosine Triphosphate Protein Multimerization Protein Binding |
| Zdroj: | Structure (London, England : 1993). 22(4) |
| ISSN: | 1878-4186 |
| Popis: | SummaryGTPases are molecular switches that control numerous crucial cellular processes. Unlike bona fide GTPases, which are regulated by intramolecular structural transitions, the less well studied GAD-GTPases are activated by nucleotide-dependent dimerization. A member of this family is the translocase of the outer envelope membrane of chloroplast Toc34 involved in regulation of preprotein import. The GTPase cycle of Toc34 is considered a major circuit of translocation regulation. Contrary to expectations, previous studies yielded only marginal structural changes of dimeric Toc34 in response to different nucleotide loads. Referencing PELDOR and FRET single-molecule and bulk experiments, we describe a nucleotide-dependent transition of the dimer flexibility from a tight GDP- to a flexible GTP-loaded state. Substrate binding induces an opening of the GDP-loaded dimer. Thus, the structural dynamics of bona fide GTPases induced by GTP hydrolysis is replaced by substrate-dependent dimer flexibility, which likely represents a general regulatory mode for dimerizing GTPases. |
| Databáze: | OpenAIRE |
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