Engineered modular heterocyclic-diamidines for sequence-specific recognition of mixed AT/GC base pairs at the DNA minor groove?

Chemical Science Pub Date: 2021-11-02 DOI: 10.1039/D1SC04720E

Abstract

This report describes a breakthrough in a project to design minor groove binders to recognize any sequence of DNA. A key goal is to invent synthetic chemistry for compound preparation to recognize an adjacent GG sequence that has been difficult to target. After trying several unsuccessful compound designs, an N-alkyl-benzodiimidazole structure was selected to provide two H-bond acceptors for the adjacent GG-NH groups. Flanking thiophenes provide a preorganized structure with strong affinity, DB2831, and the structure is terminated by phenyl-amidines. The binding experimental results for DB2831 with a target AAAGGTTT sequence were successful and include a high ΔTm, biosensor SPR with a KD of 4 nM, a similar KD from fluorescence titrations and supporting competition mass spectrometry. MD analysis of DB2831 bound to an AAAGGTTT site reveals that the two unprotonated N of the benzodiimidazole group form strong H-bonds (based on distance) with the two central G-NH while the central –CH of the benzodiimidazole is close to the –C[double bond, length as m-dash]O of a C base. These three interactions account for the strong preference of DB2831 for a -GG- sequence. Surprisingly, a complex with one dynamic, interfacial water is favored with 75% occupancy.

Graphical abstract: Engineered modular heterocyclic-diamidines for sequence-specific recognition of mixed AT/GC base pairs at the DNA minor groove
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