Abstract
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.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Acta Crystallographica Section D Biological Crystallography
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
