MURAL - Maynooth University Research Archive Library

    Mutation of outer-shell residues modulates metal ion co-ordination strength in a metalloenzyme

    Foo, Jee-Loon and Jackson, Colin J. and Carr, Paul D. and Kim, Hye-Kyung and Schenk, Gerhard and Gahan, Lawrence R. and Ollis, David L. (2010) Mutation of outer-shell residues modulates metal ion co-ordination strength in a metalloenzyme. Biochemistry Journal, 429. pp. 313-321.

    [img] Download (666kB)

    Share your research

    Twitter Facebook LinkedIn GooglePlus Email more...

    Add this article to your Mendeley library


    The metal ion co-ordination sites of many metalloproteins have been characterized by a variety of spectroscopic techniques and small-molecule model systems, revealingmany important insights into the structural determinants of metal ion co-ordination. However, our understanding of this fundamentally and practically important phenomenon remains frustratingly simplistic; in many proteins it is essentially impossible to predict metal ion specificity and the effects of remote ‘outer-shell’ residues on metal ion co-ordination strength are also poorly defined. This is exemplified by our inability to explain why metalloenzymes with identical metal ion co-ordination spheres, such as the closely related orthologues of bacterial PTE (phosphotriesterase) from Agrobacterium radiobacter and Pseudomonas diminuta, display different metal ion specificity and co-ordination strength. In the present study, we present a series of PTE variants that all possess identical metal ion co-ordination spheres, yet display large differences in their metal ion co-ordination strength. Using measurement of the rates of metal ion dissociation from the active site alongside analysis of structural data obtained through X-ray crystallography,we showthat ‘outer-shell’ residues provide essential support for the metal ion ligands, in effect buttressing them in their optimal orientation. Remote mutations appear to modulate metal ion interactions by increasing or decreasing the stabilizing effects of these networks. The present study therefore provides a description of how the greater protein fold can be modified to ‘tune’ the strength of metal ion co-ordination and metal ion specificity, as well as reinforcing the concept of proteins as ensembles of conformational states with unique structures and biochemical properties.

    Item Type: Article
    Keywords: directed evolution; metal ion binding; metal ion co-ordination; phosphotriesterase (PTE);
    Academic Unit: Faculty of Science and Engineering > Chemistry
    Item ID: 3717
    Depositing User: Gary Schenk
    Date Deposited: 31 May 2012 14:11
    Journal or Publication Title: Biochemistry Journal
    Publisher: Biochemical Society
    Refereed: Yes
      Use Licence: This item is available under a Creative Commons Attribution Non Commercial Share Alike Licence (CC BY-NC-SA). Details of this licence are available here

      Repository Staff Only(login required)

      View Item Item control page


      Downloads per month over past year

      Origin of downloads