Avidin engineering – toward the development of innovative biotech tools
The principle of avidin/biotin molecular clip is exploited for a long time for biotechnological and diagnostic purposes. Based on its extremely high affinity for biotine, avidin is mainly used to specifically link proteins (eg antibody or antigen) or nucleic acids with detection or capture systems. More recently, molecular engineering of avidin has expanded application possibilities of this protein (Nordlund et al., 2005; Riihimäki et al., 2011; Leppiniemi et al., 2011). As an example of such possibilities, Riihimäki et al. tailored avidin binding properties by mutagenesis in order to obtain a testosterone binding protein with a kd around 9 μM. Note that this work led to the production of an avidin mutant for which the biotin binding has been superseded by the steroid binding property. Hence, by this way, they developed a novel steroid receptor that could be used for diagnostic or dosage applications. Interestingly, by contrast to classical detection systems involving antibodies, this kind of engineered avidin could be used in harsh experimental conditions; antibodies are indeed known to have several drawbacks such as a low stability, a chemical sensitivity of the antigen-binding site and a large size. Robustness of avidin towards temperature, pH or ionic strength makes it a perfect tool for in vitro assays and the possibility to modify its binding properties opens new avenues for the development of assessment means of countless small molecules such as hormones or vitamins.
Nordlund HR, Vesa P. Hytönen, Jarno Hörhä, Juha A. E. Määttä, Daniel J. White, Katrin Halling, Eevaleena J. Porkka, J. Peter Slotte, Olli H. Laitinen, Markku S. Kulomaa. 2005. Tetravalent single-chain avidin: from subunits to protein domains via circularly permuted avidins. Biochem J. 392(3): 485–491.
Riihimäki TA, Soili Hiltunen, Martina Rangl, Henri R Nordlund, Juha AE Määttä, Andreas Ebner, Peter Hinterdorfer, Markku S Kulomaa, Kristiina Takkinen, Vesa P Hytönen. 2011. Modification of the loops in the ligand-binding site turns avidin into a steroid-binding protein. BMC Biotechnol. 11: 64.
Leppiniemi J, Juha A. E. Määttä, Henrik Hammaren, Mikko Soikkeli, Mikko Laitaoja, Janne Jänis, Markku S. Kulomaa, Vesa P. Hytönen. 2011. PLoS One 6(1): e16576.