1PVV

Refined structure of Pyrococcus furiosus ornithine carbamoyltransferase at 1.87 A.

(2003) Acta Crystallogr D Biol Crystallogr 59: 2140-2149

• PubMed: 14646072 Search on PubMed
• DOI: https://doi.org/10.1107/s0907444903019231
• Primary Citation of Related Structures:  
  1PVV


• PubMed Abstract: 
  

  Using synchrotron radiation, X-ray data have been collected from Pyrococcus furiosus ornithine carbamoyltransferase (Pfu OTCase) to a maximal resolution of 1.87 A, allowing the refinement of a previous structure at 2.7 A [Villeret et al. (1998), Proc. Natl Acad. Sci. USA, 95, 2801-2806]. Thanks to the high resolution of this refined structure, two sulfate ions and 191 water molecules could be localized directly from the electron-density maps. The identification of these molecules allowed a more rigorous description of the active site and the identification of residues involved in binding carbamoyl phosphate. The improved quality of the model resulted in a better definition of several loops and the various interfaces. The dodecameric protein is composed of four catalytic trimers disposed in a tetrahedral manner. The extreme thermal stability of Pfu OTCase is mainly the result of the strengthening of the intersubunit interactions in a trimer and oligomerization of the trimers into a dodecamer. Interfaces between monomers in a catalytic trimer are characterized by an increase in ion-pair networks compared with mesophilic OTCases. However, the interfaces between catalytic trimers in the dodecameric oligomer are mainly hydrophobic and also involve aromatic-aromatic and cation-pi interactions.

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Organizational Affiliation: 

Department of Microbiology, Vrije Universiteit Brussel, B-1070 Brussels, Belgium. jan.massant@vub.ac.be