2A8G: Structure Of Avidin In Complex With The Ligand Deoxyguanosine

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.
PDB ID: 2A8GDownload
MMDB ID: 39028
PDB Deposition Date: 2005/7/8
Updated in MMDB: 2017/11
Experimental Method:
x-ray diffraction
Resolution: 1.99  Å
Source Organism:
Similar Structures:
Biological Unit for 2A8G: tetrameric; determined by author and by software (PISA,PQS)
Molecular Components in 2A8G
Label Count Molecule
Proteins (4 molecules)
Avidin(Gene symbol: AVD)
Molecule annotation
Chemicals (6 molecules)
* Click molecule labels to explore molecular sequence information.

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