An enzyme-linked immunosorbent assay for the detection of agents which interfere with the DNA binding activities of transcription factors--exemplified by NF-IL6.

Binding of transcription factors to DNA is usually detected by the electrophoretic mobility shift assay also known as gel-shift or band-shift assay. Recently the use of biosensors has allowed factor/DNA interactions to be followed in real time. However, neither of these approaches lends itself easily to high-throughput screening of agents which might interfere with this process. We have therefore developed a 96-well plate-based enzyme-linked immunosorbent assay for this purpose. Biotinylated oligonucleotides bound to streptavidin-coated plates are used to capture recombinant transcription factor proteins which can then be detected using specific antibodies which in turn are recognised by peroxidase-conjugated antisera. The peroxidase catalyzes conversion of a colorless substrate to a colored product which can be quantified by optical densitometry on a plate reader. Agents which interfere with the binding of the transcription factor to DNA reduce the optical density in the well. Using the NF-IL6 transcription factor we show that the assay can detect reductions to 86% at significant levels. The assay may be readily adapted for robotic manipulation, making it ideal for high-throughput screening.

Synthesis of preparative amounts of biologically active interleukin-6 using a continuous-flow cell-free translation system.

Cell-free synthesis of preparative amounts of interleukin-6 (IL-6) in a wheat germ extract is described. Following transcription of uncapped mRNA by SP6 polymerase, protein was synthesized in a continuous flow of translation components. The system remained active for at least 50 h, producing 1.25 x 10(6) units of IL-6. Recovered IL-6 was > 80% pure, reacted with anti-IL-6 polyclonal antiserum in Western blots, and had a specific activity comparable to recombinant IL-6 purified from Escherichia coli. This is the first time biologically active IL-6 has been prepared in preparative amounts using a continuous-flow cell-free translation system and confirms the feasibility of using enhanced in vitro translation for rapid synthesis of proteins from cloned templates.