Structural studies on the 2.25-MDa homomultimeric phosphoenolpyruvate synthase from Staphylothermus marinus
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X-Ray Crystallography to Study the Oligomeric State Transition of the Thermotoga maritima M42 Aminopeptidase TmPep1050
Published on: May 13, 2020
G Harauz1, C Cicicopol, R Hegerl
1Abteilung Molekulare Strukturbiologie, Max-Planck-Institut für Biochemie, Am Klopferspitz 18a, Martinsried bei München, D-82152, Germany.
Abstract:
The phosphoenolpyruvate synthase of the hyperthermophilic archaeon Staphylothermus marinus forms an unusually large homomultimeric complex of 93 kDa subunits. Electron image analysis of negatively stained and low-dose unstained preparations showed that the complex has a single, stable characteristic view and a well-preserved core with threefold rotational symmetry. The periphery of the assembly is composed of a nebulous, possibly flexible, component. Mass measurements by scanning transmission electron microscopy yielded a molecular weight of 2250 +/- 230 kDa, confirming the well-defined nature of the structure and indicating that it is composed of 24 +/- 2.5 subunits. The stability and symmetry of the characteristic projection views suggest a polyhedral three-dimensional architecture. The novel quaternary arrangement of this enzyme might be a consequence of its adaptation to an extreme environment.
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