1. X-ray study of the conformational changes in the molecule of phosphopantetheine adenylyltransferase from Mycobacterium tuberculosis during the catalyzed reaction.
- Author
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Timofeev, Vladimir, Smirnova, Evgenia, Chupova, Larisa, Esipov, Roman, and Kuranova, Inna
- Subjects
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CONFORMATIONAL analysis , *X-ray crystallography , *PHOSPHOPANTETHEINE , *TRANSFERASES , *MYCOBACTERIUM tuberculosis , *CATALYSIS , *SUBSTRATES (Materials science) , *ADENOSINE triphosphate - Abstract
Structures of recombinant phosphopantetheine adenylyltransferase (PPAT) from Mycobacterium tuberculosis (PPATMt) in the apo form and in complex with the substrate ATP were determined at 1.62 and 1.70 Å resolution, respectively, using crystals grown in microgravity by the counter-diffusion method. The ATP molecule of the PPATMt-ATP complex was located with full occupancy in the active-site cavity. Comparison of the solved structures with previously determined structures of PPATMt complexed with the reaction product dephosphocoenzyme A (dPCoA) and the feedback inhibitor coenzyme A (CoA) was performed using superposition on Cα atoms. The peculiarities of the arrangement of the ligands in the active-site cavity of PPATMt are described. The conformational states of the PPAT molecule in the consequent steps of the catalyzed reaction in the apo enzyme and the enzyme-substrate and enzyme-product complexes are characterized. It is shown that the binding of ATP and dPCoA induces the rearrangement of a short part of the polypeptide chain restricting the active-site cavity in the subunits of the hexameric enzyme molecule. The changes in the quaternary structure caused by this rearrangement are accompanied by a variation of the size of the inner water-filled channel which crosses the PPAT molecule along the threefold axis of the hexamer. The molecular mechanism of the observed changes is described. [ABSTRACT FROM AUTHOR]
- Published
- 2012
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