2a5c
Structure of Avidin in complex with the ligand 8-oxodeoxyadenosine
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OverviewOverview
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.
About this StructureAbout this Structure
2A5C is a Single protein structure of sequence from Gallus gallus with NAG and 8DA as ligands. Full crystallographic information is available from OCA.
ReferenceReference
Recognition of oxidatively modified bases within the biotin-binding site of avidin., Conners R, Hooley E, Clarke AR, Thomas S, Brady RL, J Mol Biol. 2006 Mar 17;357(1):263-74. Epub 2006 Jan 6. PMID:16413579
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