MBNL1-RNA recognition: contributions of MBNL1 sequence and RNA conformation.

Muscleblind-like proteins (MBNL) are RNA-binding proteins that bind to the poly(CUG) and poly(CCUG) sequences that are the causative agents of myotonic dystrophy. It has been suggested that as a result of binding to the repeating RNA sequences, MBNL1 is abnormally expressed and translocated, which leads to many of the misregulated events in myotonic dystrophy. In this work, steady-state fluorescence quenching experiments suggest that MBNL1 alters the structure of helical RNA targets upon binding, which may explain the selectivity of MBNL1 for less structured RNA sites.

Selective inhibition of MBNL1-CCUG interaction by small molecules toward potential therapeutic agents for myotonic dystrophy type 2 (DM2).

Myotonic dystrophy type 2 (DM2) is an incurable neuromuscular disease caused by expanded CCUG repeats that may exhibit toxicity by sequestering the splicing regulator MBNL1. A series of triaminotriazine- and triaminopyrimidine-based small molecules (ligands 1-3) were designed, synthesized and tested as inhibitors of the MBNL1-CCUG interaction. Despite the structural similarities of the triaminotriazine and triaminopyrimidine units, the triaminopyrimidine-based ligands bind with low micromolar affinity to CCUG repeats (K(d) ∼ 0.

Cooperative binding of a quinoline derivative to an RNA stem loop containing a dangling end.

The binding of a quinoline derivative (QD2) to a small RNA stem loop containing a 3'-dangling end (RNA1) has been studied. The compound was identified by first performing a similarity search of the NCI database of 250,000 compounds and then using computational docking with autodock to evaluate the binding of the resulting compounds to RNA1. Binding experiments using fluorescence and ITC methods revealed that QD2 binds cooperatively to four binding sites on RNA1 with equilibrium binding dissociation constants ranging from 8.

A simple ligand that selectively targets CUG trinucleotide repeats and inhibits MBNL protein binding.

This work describes the rational design, synthesis, and study of a ligand that selectively complexes CUG repeats in RNA (and CTG repeats in DNA) with high nanomolar affinity. This sequence is considered a causative agent of myotonic dystrophy type 1 (DM1) because of its ability to sequester muscleblind-like (MBNL) proteins. Ligand 1 was synthesized in two steps from commercially available compounds, and its binding to CTG and CUG repeats in oligonucleotides studied.

Molecular recognition of a thymine bulge by a high affinity, deazaguanine-based hydrogen-bonding ligand.

7-Deazaguanine (7-DeG) was developed as a hydrogen-bonding module capable of enhanced recognition of uracil (U) and thymine (T); a water-soluble derivative displayed high affinity and selectivity toward DNA and RNA duplexes containing single T- and U-bulges.