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Thermodynamic properties of damaged DNA and its recognition by xeroderma pigmentosum group A protein and replication

Viktor Brabec1, Kristýna Stehlíková, Jaroslav Malina

  • 1Institute of Biophysics, Academy of Sciences of the Czech Republic, Královopolská 135, CZ-61265 Brno, Czech Republic. brabec@ibp.cz

Archives of Biochemistry and Biophysics
|January 13, 2006
PubMed

Insights

Platinum-induced DNA adducts alter DNA stability and protein binding. Rigid DNA bending determines XPA protein affinity, while RPA binds to interrupted DNA base pairs, independent of stability changes.

Area of Science:

  • Molecular Biology
  • Biochemistry
  • DNA Damage and Repair

Background:

  • Cis-diamminedichloroplatinum(II) (cisplatin) is a widely used chemotherapy drug that forms intrastrand DNA adducts.
  • These adducts can distort DNA structure and affect DNA-protein interactions, which are crucial for DNA repair and cellular processes.

Purpose of the Study:

  • To investigate the impact of specific cisplatin-induced DNA adducts (1,2-GG and 1,3-GTG) on DNA energetics.
  • To correlate these energetic changes with the binding affinities of xeroderma pigmentosum A (XPA) and replication factor A (RPA) proteins to damaged DNA.

Main Methods:

  • Differential scanning calorimetry (DSC) was used to measure the thermodynamic stability of DNA duplexes containing specific adducts.
  • Gel electrophoresis was employed to assess the binding affinity of XPA and RPA proteins to the damaged DNA duplexes.

Main Results:

  • Rigid DNA bending induced by adducts is a key factor for high-affinity XPA binding.
  • Changes in DNA thermodynamic stability also significantly influence XPA affinity.
  • RPA protein preferentially binds to DNA with disrupted base-pairing hydrogen bonds.
  • RPA binding affinity is unaffected by alterations in the thermodynamic stability of the damaged DNA.

Conclusions:

  • DNA adduct-induced structural changes, particularly bending and thermodynamic stability, play critical roles in modulating the interactions of DNA repair proteins like XPA.
  • RPA exhibits a distinct binding mechanism, favoring DNA distortions with interrupted hydrogen bonds and showing independence from overall DNA thermodynamic stability.

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