Re-pairing DNA: binding of a ruthenium phi complex to a double mismatch

Area of Science:

• Coordination Chemistry
• Structural Biology
• DNA Damage and Repair

Background:

• DNA mismatches are critical lesions that can lead to mutations if not repaired.
• Ruthenium complexes are explored for their potential in DNA binding and therapeutic applications.
• Understanding metallo-DNA interactions provides insights into novel binding mechanisms.

Purpose of the Study:

• To elucidate the atomic-level structural basis of ruthenium complex binding to a specific DNA double mismatch.
• To characterize the metalloinsertion interaction at a TA mismatch with a flipped-out thymine and adenine bulge.
• To identify a novel DNA binding mode for ruthenium complexes involving major groove insertion.

Main Methods:

• X-ray crystallography at 0.9 Å atomic resolution.
• Detailed structural analysis of ruthenium complex-DNA interactions.
• Characterization of metalloinsertion and groove binding modes.

Main Results:

• Determined the crystal structure of a ruthenium complex bound to a TA DNA mismatch with a flipped-out thymine and adenine bulge.
• Identified a metalloinsertion interaction of Λ-[Ru(phen)2phi]2+ at the adenine bulge via the major groove.
• Observed specific interactions between DNA adenines and ruthenium phen ligands.
• Described a secondary binding mode of a Δ-[Ru(phen)2phi]2+ complex via the minor groove, with its phi ligand sandwiched between others.

Conclusions:

• The study reveals a new form of metalloinsertion involving major groove binding of ruthenium complexes.
• The findings offer a detailed atomic understanding of how ruthenium complexes interact with DNA mismatches.
• This work expands the known repertoire of metallo-DNA interactions and their structural basis.