DNA-protein cross-links: Formidable challenges to maintaining genome integrity

Area of Science:

• Molecular Biology
• Genetics
• Biochemistry

Background:

• DNA-associated proteins are crucial for DNA folding and transactions.
• DNA-protein cross-links (DPCs) form when proteins covalently bind to DNA due to chemical agents or radiation.
• Abortive DPCs arise from trapped DNA-metabolizing enzymes, often at DNA strand breaks.

Purpose of the Study:

• To elucidate the challenges posed by DPCs to genome integrity and gene expression.
• To review and understand the mechanisms of DPC repair.

Main Methods:

• In vitro studies examining the impact of DPCs on DNA helicases and polymerases.
• Analysis of existing models for direct and indirect DPC removal.
• Investigation of proteasomal and protease-mediated degradation of cross-linked proteins.

Main Results:

• DPCs cause steric hindrance, impeding DNA replication and transcription by enzymes like helicases and polymerases.
• Direct DPC repair involves complexes like Mre11-Rad50-Nbs1 for specific topoisomerase 2-linked DPCs.
• Indirect repair involves proteases (Wss1, Sprtn) degrading proteins, leaving peptide-cross-links.

Conclusions:

• DPCs present significant obstacles to maintaining genome stability and gene expression.
• Both direct cleavage and indirect protein degradation are key DPC repair strategies.
• The processing of peptide-cross-links after protein removal remains an area needing further research.