Probing H3K9me3 Using Engineered Recombinant Protein Probes

Trimethylation of H3K9 (H3K9me3) is an important epigenetic modification that is associated with gene repression and silencing. Detection and quantification of H3K9me3 is critically important for understanding its role in epigenetic regulation and potential applications of H3K9me3-based diagnostic or prognostic assays. The current detection approaches, however, depend on the use of commercial antibodies, which are costly and exhibit significant quality variations among suppliers. Here, we have designed a sensor based on recombinant proteins expressed in E. coli. The sensor can recognize H3K9me3 with high accuracy and comparable sensitivity to commercial antibodies. The production cost and batch-to-batch variations of our sensor is significantly lower compared to antibodies. Our sensor thus offers a useful alternative tool for the detection of H3K9me3. Extension of our engineering scheme to other important epigenetic marks will also be discussed.