2A5B

Recognition of oxidatively modified bases within the biotin-binding site of avidin.

(2006) J Mol Biol 357: 263-274

• PubMed: 16413579 Search on PubMed
• DOI: https://doi.org/10.1016/j.jmb.2005.12.054
• Primary Citation of Related Structures:  
  2A5B, 2A5C, 2A8G


• PubMed Abstract: 
  

  Oxidative damage of DNA results in the formation of many products, including 8-oxodeoxyguanosine, which has been used as a marker to quantify DNA damage. Earlier studies have demonstrated that avidin, a protein prevalent in egg-white and which has high affinity for the vitamin biotin, binds to 8-oxodeoxyguanosine and related bases. In this study, we have determined crystal structures of avidin in complex with 8-oxodeoxyguanosine and 8-oxodeoxyadenosine. In each case, the base is observed to bind within the biotin-binding site of avidin. However, the mode of association between the bases and the protein varies and, unlike in the avidin:biotin complex, complete ordering of the protein in this region does not accompany binding. Fluorescence studies indicate that in solution the individual bases, and a range of oligonucleotides, bind to avidin with micromolar affinity. Only one of the modes of binding observed is consistent with recognition of oxidised purines when incorporated within a DNA oligomer, and from this structure a model is proposed for the selective binding of avidin to DNA containing oxidatively damaged deoxyguanosine. These studies illustrate the molecular basis by which avidin might act as a marker of DNA damage, although the low levels of binding observed are inconsistent with the recognition of oxidised purines forming a major physiological role for avidin.

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Organizational Affiliation: 

Department of Biochemistry, University of Bristol, Bristol BS8 1TD, UK.