Plant immunophilins: functional versatility beyond protein maturation

Authors

  • Patrick Romano,

    Corresponding author
    1. Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK;
    2. Department of Plant and Microbial Biology, Koshland Hall, University of California, Berkeley, CA 94720, USA
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  • Julie Gray,

    1. Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK;
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  • Peter Horton,

    1. Department of Molecular Biology and Biotechnology, University of Sheffield, Firth Court, Western Bank, Sheffield S10 2TN, UK;
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  • Sheng Luan

    1. Department of Plant and Microbial Biology, Koshland Hall, University of California, Berkeley, CA 94720, USA
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Author for correspondence: Patrick Romano Tel: +44 114 2224244 Fax: +44 114 2222712 Email: P.Romano@sheffield.ac.uk

Abstract

Contents

  • Summary 1

  • I. A historical perspective 2
  • II. The mechanism of immunosuppression 2
  • III. PPIase activity and protein folding 3
  • IV. Immunophilins are ubiquitous proteins 3
  • V. Plant immunophilins 5
  • VI. Specific functions of plant immunophilins 7
  • VII. Concluding remarks 13
  • References 13

Summary

Originally identified as the cellular targets of immunosuppressant drugs, the immunophilins encompass two ubiquitous protein families: the FK-506 binding proteins or FKBPs, and the cyclosporin-binding proteins or cyclophilins. Present in organisms ranging from bacteria to animals and plants, these proteins are characterized by their enzymatic activity; the peptidyl–prolyl cis–trans isomerization of polypeptides. Whilst this function is important for protein folding, it has formed the functional basis for more complex interactions between immunophilins and their target proteins. Beginning with a brief historical overview of the immunophilin family, and a representative illustration of the current state of knowledge that has accumulated for these proteins in diverse organisms, a detailed description is presented of the recent advances in the elucidation of the role of this ubiquitous protein family in plant biology. Though still in its infancy, investigation into the function of plant immunophilins has so far yielded interesting results – as a significant component of the chloroplast proteome, the abundance of immunophilins located in the thylakoid lumen suggests that these proteins may play important roles in this relatively uncharacterized subcellular compartment. Moreover, the importance of the complex multidomain immunophilins in functions pertaining to development is underscored by the strong phenotypes displayed by their corresponding mutants.

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