1j3b

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Crystal structure of ATP-dependent phosphoenolpyruvate carboxykinase from Thermus thermophilus HB8

Overview

In order to understand the induced fit and the thermostabilization, mechanisms of ATP-dependent phosphoenolpyruvate carboxykinase, the crystal, structure of the enzyme from the extreme thermophile Thermus thermophilus, HB8 (TtPEPCK) was determined and compared with those of orthologues of, known structure from two mesophilic organisms. The protomer structures in, these orthologues, which exhibit open/closed interdomain conformations, are similar. Isomorphous crystals of unliganded and ATP-bound TtPEPCK were, obtained. The asymmetric units of both crystal forms contain two protomers, A and B with closed and open conformations, respectively. ATP was only, observed in the interdomain cleft of the closed protomer, suggesting that, the induced fit of TtPEPCK agrees with the so-called ;conformational, selection' mechanism where ligand binding is not essential for domain, closure although its binding leads to the stabilization of the closed, state. A bound calcium observed in the N-terminal domain of TtPEPCK, probably contributes to the thermal stability. A combination of, hydrophobic effects, ion pairs and entropic effects might also contribute, to the thermostability of TtPEPCK.

About this Structure

1J3B is a Single protein structure of sequence from Thermus thermophilus with CA, PO4 and GOL as ligands. Full crystallographic information is available from OCA.

Reference

Structure of ATP-dependent phosphoenolpyruvate carboxykinase from Thermus thermophilus HB8 showing the structural basis of induced fit and thermostability., Sugahara M, Ohshima N, Ukita Y, Sugahara M, Kunishima N, Acta Crystallogr D Biol Crystallogr. 2005 Nov;61(Pt 11):1500-7. Epub 2005, Oct 19. PMID:16239727

Page seeded by OCA on Sat Nov 24 23:01:57 2007