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Updated: May 11, 2026

X-Ray Crystallography to Study the Oligomeric State Transition of the Thermotoga maritima M42 Aminopeptidase TmPep1050
Published on: May 13, 2020
Pyrococcus horikoshii TET2 peptidase assembling process and associated functional regulation
Alexandre Appolaire1, Eva Rosenbaum, M Asunción Durá
1Institut de Biologie Structurale, CNRS, UMR5075, F-38027/Commissariat à l'Energie Atomique, F-38054/Université Joseph Fourier, F-38027 Grenoble, France.
Tetrahedral (TET) aminopeptidases assemble into large structures. This study reveals that TET2 enzyme assembly is an ordered process, with dimers forming hexamers and then dodecamers, activating its peptide degradation function.
Area of Science:
- Biochemistry
- Structural Biology
- Enzymology
Background:
- Tetrahedral (TET) aminopeptidases are large protein complexes involved in polypeptide degradation.
- Understanding their assembly is crucial for elucidating their biological function.
Purpose of the Study:
- To investigate the assembly pathway and regulation of Tetrahedral (TET) aminopeptidases using Pyrococcus horikoshii TET2 (PhTET2) as a model.
- To characterize the structural and functional properties of assembly intermediates.
Main Methods:
- X-ray crystallography
- Small-angle X-ray scattering (SAXS)
- Analytical ultracentrifugation
- Native gel electrophoresis
- Electron microscopy
- Peptide degradation assays
Main Results:
- A stable, catalytically active dimeric precursor of PhTET2 was identified.
- SAXS confirmed the dimer's architecture matches that within the assembled dodecamer.
- Hexamers were identified as key intermediates in a highly ordered assembly process.
- Oligomerization was shown to trigger enzymatic activity towards large substrates.
- In vivo, both dimeric precursors and assembled TET complexes coexist.
Conclusions:
- The assembly of TET aminopeptidases is a regulated, ordered process involving dimers and hexamers.
- Oligomerization is essential for activating the enzyme's function on large substrates.
- A dimer-dodecamer equilibrium likely regulates TET activity in vivo.
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