Crosslinking of DNA



Crosslinks in protein. DNA replication is blocked by crosslinks and leads to cell death.

Agents that Crosslink DNA

I. Exogenous Cross Linking Agents

guanine on the opposite strands forming interstrand crosslink [1].

Cisplatin (cis-diamminedichloroplatinum(II) and its derivative forms DNA cross links as monoadduct, interstrand crosslink, intrastrand crosslink or DNA protein crosslink. Mostly it acts on the adjacent N-7 guanine forming 1, 2 intrastrand crosslink [2,3].

II. Endogenous Cross Linking Agents

a) Nitrous acid formed in the stomach dietary source nitrites. It induces formation of interstrand DNA crosslink at aminogroup of exocyclic N2 of guanine at the CG sequences. b) Reactive chemicals such as malondialdehyde which are formed endogenously as the product of lipid peroxidation. They create etheno adducts formed by aldehyde which undergo rearrangements to form crosslinks on opposite strands [4].

Psoralens

Psoralens are natural compounds (furocoumarins) present in plants. These compounds get activated in the presence of UV - A. They form covalent adducts with thymine [5]. The crosslinking reaction by Psoralens targets TA sequences intercalating in DNA and linking one base of the DNA with the one below it. Psoralen adducts cause replication arrest and is used in the treatment of psoriasis and vitiligo.

DNA Protein Crosslink Aldehydes such as Schiff base formation between protein and aldehyde causes this DNA protein interstrand link

Formaldehyde (HCHO) induces protein-DNA and protein-protein crosslinks, and is a common reagent of choice for molecular biology experiments.[6] These crosslinks may be reversed by incubation at 70°C.[7]


References

  1. ALI-OSMAN F. ; RAIRKAR A. ; YOUNG P., Formation and repair of 1,3-bis-(2-chloroethyl)-1-nitrosourea and cisplatin induced total genomic DNA interstrand crosslinks in human glioma cells, Cancer biochemistry biophysics (Cancer biochem. biophys.), 1995, vol. 14, no4, pp. 231-241.
  2. N Poklar, D S Pilch, S J Lippard, E A Redding, S U Dunham, and K J Breslauer,Influence of cisplatin intrastrand crosslinking on the conformation, thermal stability, and energetics of a 20-mer DNA duplex,Proc Natl Acad Sci U S A. 1996 July 23; 93(15): 7606–7611
  3. G. N. Rudd, J. A. Hartley and R. L. Souhami, Persistence of cisplatin-induced DNA interstrand crosslinking in peripheral blood mononuclear cells from elderly and young individuals, Cancer Chemotherapy and Pharmacology, Volume 35, Number 4 / July, 1995, 323-326
  4. Mathews & Vanholde, Biochemistry, 2nd Edition. Benjamin Cummings Publication
  5. Qi Wu, Laura A Christensen, Randy J Legerski & Karen M Vasquez, Mismatch repair participates in error-free processing of DNA interstrand crosslinks in human cells,EMBO reports 6, 6, 551–557 (2005).
  6. Formaldehyde Crosslinking Experiments [1]
  7. Somashe Niranjanakumaria, Erika Lasdaa, Robert Brazasa, Mariano A. Garcia-Blanco. Reversible cross-linking combined with immunoprecipitation to study RNA–protein interactions in vivo. Methods. 2002 Feb;26(2):182-90. [2]
 
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