The tetracycline aptamer is an in vitro selected RNA that binds to the antibiotic with the highest known affinity of an artificial RNA for a small molecule (Kd approximately 0.8 nM). It is one of few aptamers known to be capable of modulating gene expression in vivo. The 2.2 A resolution cocrystal structure of the aptamer reveals a pseudoknot-like fold formed by tertiary interactions between an 11 nucleotide loop and the minor groove of an irregular helix. Tetracycline binds within this interface as a magnesium ion chelate. The structure, together with previous biochemical and biophysical data, indicates that the aptamer undergoes localized folding concomitant with tetracycline binding. The three-helix junction, h-shaped architecture of this artificial RNA is more complex than those of most aptamers and is reminiscent of the structures of some natural riboswitches.
Structural basis for specific, high-affinity tetracycline binding by an in vitro evolved aptamer and artificial riboswitch.,Xiao H, Edwards TE, Ferre-D'Amare AR Chem Biol. 2008 Oct 20;15(10):1125-37. PMID:18940672
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
↑ Xiao H, Edwards TE, Ferre-D'Amare AR. Structural basis for specific, high-affinity tetracycline binding by an in vitro evolved aptamer and artificial riboswitch. Chem Biol. 2008 Oct 20;15(10):1125-37. PMID:18940672 doi:10.1016/j.chembiol.2008.09.004