Antibody-free reading of the histone code using a simple chemical sensor array.

The histone code refers to the complex network of histone post-translational modifications that control gene expression and are of high interest as drivers of a large number of human diseases. We report here on a mix-and-match toolkit of readily available dyes and calixarene host molecules that can be combined to form dye-displacement sensors that respond to a wide variety of cationic peptides. Using the data from only two or three such simple supramolecular sensors as a chemical sensor array produces fingerprints of data that discriminate robustly among many kinds of histone code elements. "Reads" that are accomplished include the discrimination of unmethylated, mono-, di-, and trimethylated lysines on a single histone tail sequence, identification of different modifications and combinations of modifications on a single histone tail sequence, identification of a single modification type in several different sequence contexts, and identification of isomeric dimethylarginine modifications. Reads that are sometimes troublesome for antibodies are achieved. We also report on the ability of the sensor array to report simultaneously on the concentrations and identities of histone modifications. This sensor array discriminates between post-translationally modified analytes without being limited to partners that contain a single, programmed binding interaction.

Attraction by repulsion: compounds with like charges undergo self-assembly in water that improves in high salt and persists in real biological fluids.

We report a family of highly anionic calixarenes that form discrete homo-dimeric assemblies in pure water, that get stronger in high salt solutions, and that remain assembled in complex, denaturing solutions like real urine. The results reveal the potential of like-charged subunits for self-assembly in high-salt solutions and biological fluids.

Synthesis of new trisulfonated calix[4]arenes functionalized at the upper rim, and their complexation with the trimethyllysine epigenetic mark.

A synthetic route to produce a new family of trisulfonated calix[4]arenes bearing a single group, selectively introduced, that lines the binding pocket is reported. Ten examples, including new sulfonamide and biphenyl-substituted hosts, each with additional binding elements, demonstrate the tuning of guest affinities and selectivities. NMR titrations in phosphate-buffered water show that one of the new hosts binds to the modified amino acid trimethyllysine with the highest affinity and selectivity observed to date.